There's no difference between getting a blowjob from a twink and a woman, actually there is, the twink will be crazed with cocklust. Just look at pic related. These two have female tier soft smooth faces, just like a woman, and cute full lips, again, just like a woman.
When it comes to anal with a man you can say yeah, there's a cock beside it, but with blowjobs there's no difference like that. Smooth soft skin and lips = virtually no different from getting it from a real girl.