Without examples its a bit hard to define but I will try to help the best way I can.
First a good spiritual director is invaluable. I cannot recommend enough one who has the Charism of spiritual direction.
A simple definition can be:
A temptation tends to be like a repeating thought almost like a tornado hoping to suck you up inside. It tends to be repeating the same basic idea over and over to get you weaken and indulge in the thought/fantasy/desire/action etc. This will lead you in contrast to teaching of Jesus and the Church. (i.e. a desire to look at porn)
OCD would result in a similar rapacious thought but it is something more benign in nature like checking if the door is locked 5, 10, or 20 times before going out of the house. At no point are you doing anything in contrast with Jesus’s teachings.
