Surely there is: except /ɪkˈsept/ and accept /əkˈsept/ totally different first vowel

When pronounced carefully, yes, there is a difference. However, it is almost always obvious which is meant from context. And the difference is pronunciation is so slight that if someone used the wrong one, most listeners would not hear it as an error, and would actually think they had heard the correct word.

You can hear these words pronounced at Dictionary.com. There are slight differences.

To a native speaker, the difference is very clear. accept [æksɛpt] / except [ɛksɛpt] For English learners, one difficulty is that English has a lot of vowels. For example, some languages have five vowels, /i/, /e/, /a/, /o/, and /u/, whereas North American English has about 14 depending on the dialect. Consider these words: beet, bit, bait, bet, bat, bot, but, boat, book, boot, bout, and bite. A learner from a language with the five vowels mentioned above will usually confuse beet/bit, bet/bat, bot/but, and book/boot. The pair bet/bat is the same difference as except/accept.

Yes. It's very faint (quiet).