How to tell a sugar daddy from a dirty old man

Someone asked me that on a date some time ago, as if she was quizzing me. For the first few seconds I thought 'Wait, isn't it the same thing?'. But then upon more mature reflection: 'Of course they are different', the dirty old man is exactly that: a dirty old man who just trolls around for young women (21+ in many states) to seduce no matter what. He would lie, cheat, and steal to accomplish his goal. Contrast that to a sugar daddy, who of course is much more, should I say, 'suave'?
Both the sugar daddy and the dirty old man have similar things in mind to a certain extent, lol, but the approach makes the difference. The SD of course becomes a good friend and a mentor as much as a lover to the lady. Besides, the SD rarely brings up the issue of sex in a direct way. He lets the situation flow casually and naturally like it would on any date. He doesn't go begging for it, with drool all over his mouth, like a dirty old man would. I guess that's the difference? I'm sure I can think of more but its getting late and I have some stock charts to look at.