Is there a difference between the verbs "bieten" and "anbieten" in sense "to offer"?
There are some typical uses where one fits much more than the other: For example one would say:
IMO nobody would say "anbieten" in this context. Another case would be such context like offering a seat or refreshments:
Here only "anbieten" fits (I don't know the exact reason, just that I would register "bieten" as odd).
As other answers already stated, there are areas where both are fine.
That means offer help, with using
But you can say the following:
Here you can't use
In general, you can use