I don’t have V15 type IV, but I have a type III which I like.
I also have an M75E. I like it to.
They sound similar in that they sound like Shure. Both fitted with OEM stylus I say the Type III is more detailed and elegant. Better? Yes, but it should be based on their cost back in the day. The M75 was very common and very good. It’s like the M91 which is like the V-15 Type II.
A lot of it will depend on the stylus - OEM or aftermarket. There are excellent aftermarket options for Shure, which is great because OEM are very rare.
If your looking for diversity in sound presentation they both sound like Shure, again the stylus will be the big difference. There are tons of stylus options for the M75 body.