seems to be a buzz-word in our business (engineering products) and trying to translate it into German is often problematic. It very often seems redundant in relation to the rest of the sentence.
[We always say in this office that we have to translate the English, written by our colleagues for things like catalogues, into proper English before we can translate into German!]
Basically, the difference to me (BE) can be described as follows:
Offering, as in 'product offering', simply means something like 'product range' and is akin to „Programm“ or „Palette“.
Offer, as in „Angebot“, means 'quotation'.
I realise that others may have other ideas, but the above is my experience.