Yes, they’re totally different. The Sterling by Musicman SUBs are not produced by Ernie Ball, but in Asia by Praxis Instruments under license from Ernie Ball.
The US SUBs were discontinued around 2010. The Sterling by Musicman SUBs (also known as the Ray4 and Ray5) are still being produced, and have nothing to do with either the original SUBs or the Musicman Sterling, but are the lowest tier on the Asian-produced Stingray value line.
The naming conventions are confusing, but as long as you remember that Sterling by Musicman (SBMM in TB parlance) is produced in Asia under license, and Ernie Ball Musicman (EBMM to us TB’ers) is produced in the US, it’s not too difficult. Here is a chart I made earlier:
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Mine is a NOS US-made SUB Sterling, not a "Sterling by Music Man." It had apparently been sitting in the Ernie Ball warehouse for over a decade before it was purchased by NJ Guitar and Bass Center.

