Why does TurboTax say my refund was accepted but the IRS does not say accepted yet?

Yes, the IRS and TurboTax use different terms to describe the very different steps they take in the e-filing process. 

When you e-file your tax return, it's Pending, then Accepted. Accepted means the IRS has your return, and TurboTax no longer is involved with the processing of your return. 

The IRS steps are:

 

1. Return Received -  the IRS has your return and is processing it.
2. Refund Approved - the IRS has finished processing and has approved your refund.
3. Refund Sent - the check has been issued, or the deposit scheduled.

ACCEPTED means "in the hands of" the IRS. Turbotax  has done its job.

RECEIVED means the same thing. Maybe you mailed it in.