=> referring to cambridge online dictionary:
Definition
How about...?
1 INFORMAL used to make a suggestion:
How about the cinema tonight?
How about going to the cimena?
2 used when asking someone about a different thing:
You don't eat meat, do you? How about fish?

Definition
what about?
used to suggest something:
What about Lola - shall we invite her?
What about taking a few days off?

Definition
How/What about?
used when suggesting or offering something to someone:
How about a trip to the zoo this afternoon?
"Coffee, Sarah?" "No, thanks." "What about you, Kate?"


actually I always thaought that how about refers to a thing or something you do (how about doing sth./ how about some food), and what about refers to a person (what about chris? doesn't he want to eat?). but actually you also can say what about yesterday? didn't you have fun?

.... I guess that this is quite a difficult topic, since one would think, we can trust cambridge dictionaries. but I certainly believe there is a difference

analog zum deutschen "wie wäre es (mit)" und ""was ist mit"
Also in weilas Beispielen:

Wie wäre es mit einer Tasse Kaffee, Sarah? (= How about a cup...)
Und was ist mit Dir, Kate? (= What about you...)

Is there really nobody else willing to share their view on this subject?
:-(

@Weila: I'm a native speaker (admittedly from Northern England, so my ideas may not be universal) but in all your examples both How and What sound equally good. I can't think of an example when you could use one but not the other, to me they are the same

I agree with Dave. They are as near the same as makes no difference.
And I'm admittedly from the south ;-)

Both sound equally good, though admittedly I'm from the colonies.

I admit to being a part of this global conspiracy. I've never noticed any significant difference either. (-:


@ebi:
>when I read that according to ... there be no
>difference between these two expressions, both
>of which be used

Were you just checking to see if anyone was paying attention? Just in case, I hope you won't mind my mentioning that 'be' doesn't work here. Use 'according to ... there was no difference' if you want to stress that it's only hearsay, 'there is no difference' if you accept it as fact. And probably 'both of which are used' in either case; 'both of which were used' is getting so far removed from the source of the reported speech that it sounds misleadingly like past tense.

>In both cases one be asking

'In both cases one is asking,' if you believe what you're saying; 'in both cases one would be asking,' if you're just offering it as a hypothesis.

In a nutshell: The present subjunctive is not used in standard (non-dialect) modern English for reported speech.

>Many thanks for enlightening.

Transitive verb: 'for enlightening me / for enlightenment.'

@hm -- us:
> Were you just checking to see if anyone was paying attention?

If I affirmed this I would admittedly lie.

> Just in case, I hope you won't mind my mentioning ...

Nothing I could do less!
Far from it, I rather want to express my sincere thanks for your corrections and taking the time to reply that thoroughly at all.
It really seems to me that I completely messed it up when I indeed wanted to indicate the reported speech by using the subjunctive.
I absolutely could comprehend your first objection but was a bit amazed that you wrote

> The present subjunctive is not used in standard (non-dialect) modern English for reported speech.

When I was writing the initial posting I recalled an example from some grammar book which read: "(Someone) requested that the parking lot be closed at night."
But, in fact, this is no reported speech.
I guess this might habe been misleading me that sorely.
The funny thing is that I had to lecture on the usage of the subjunctive in German language lately -- with a stress on the fact that Konjunktiv II is widely misused where Konjunktiv I is required. This is [and unfortunately becomes more and more] common but is considered as wrong all the same.
So it appears that there was a bit too much subjunctive lately -- and I have obviously overdone the whole thing ...
;-)
But, taking this as an encouragement, I will refer to the usage of subjunctive mood in English once more and in detail ASAP.

> Transitive verb: 'for enlightening me / for enlightenment.'

Aaarghhh, and it DID look somewhat strange, but I was too lazy (ignorant?) to look it up!
Now, as I read it, "enlightenment", naturally.
:-/

Many thanks once more.

Those go as well to all other contributors who surprisingly made clear that my teacher 15 years ago was wrong (if only I could recall her "definition" ...) and I could not care less whether to say "how about" or "what about" in the future.
:-)

I admit that it seems absolutely reasonable to think that "how about" and "what about" are equivalent, but if they were, why would they co-exist if not for slight differences?

Or else how come that a rather random google search produces about 17.400 instances of the phrase "how about a cup of coffee", but only around 150 instances of "what about a cup of coffee" if there weren't a distinction that (presumably native) speakers make?

In fact I do have evidence from a (rather small sample) of Canadian speakers of English that shows a distribution which totally matches the distinction between "wie wäre es mit X" and "was ist mit X" in German (54 instances of "how/what about" in total. 41 instances of "how about" translatable as "wie wäre es mit", 13 instances of "what about" translatable as "was ist mit").

A similar sample from German learners of English shows an exclusive use of "what about" in any of the two options - which is acceptable, of course, but does not seem to match what the Canadian speakers of English were doing (and they were not from Québec in terms of their first language).

@Slightly off topic - In Northern Ireland,at least in Belfast,'what about' and 'how about' are common greetings, replacing 'how are you ? or 'how do you do?' Sometimes, when the 'how' version is used an 'S' is inserted 'how's'.
It is not unusual to hear friends greet each other, "ach!Sammy,how/how's about ye? or " Ach!what about ye Sammy?". It is basically an invitation to Sammy to tell all about himself and what has happened to him since last they met,an invitation to have a chat.

Ich hatte immer gedacht:
- "how about": to suggest sth. (because I have an idea)
- "what about": to enquire about sth. (because I am interested)

Examples:
"How about the cinema?" - Wie wär's mit Kino?
"What about Lola?" - Was ist mit Lola? (needs context to turn into a suggestion, e.g. "shall we invite her")
"What about yesterday?" - Was war denn (mit) gestern? = enquiry, not a suggestion.

Now I'd like to know, is "What about taking a few days off?" a suggestion or a question? And if it is meant as a suggestion, doesn't "how about..." sound more natural?

@Andi:

it doesn't depend on the wording, imo, but on the emphasis.

"how about taking a few days off" could be a suggestion, or a question, or a suggestive question, depending on the tone of voice. if you want to make certain in written form, then you will have to re-phrase it to, for instance: I suggest you take a few days off

Notwithstanding my posting further above, I do agree with Lindschluder. But please note the initial question used "how/what about" in a specific context, where there is very little difference between the two phrases.

In other uses I believe the two do differ.
Thus one uses "how about" as a offer (e.g. "How about some coffee?"), especially when broaching a topic for the first time.
e.g. If someone visits you and you offer "how about some coffee?", they could say "no thanks, I can't sleep if I drink coffee at this time of night." You could then ask: "what about a cup of tea?" (also possible: "how about"). But I wouldn't use "what about" if offering a drink the first time.