For most collectors, the only time you will have any problems with separating the hyphen-hole perforation from the hyphen roulette is if you collect US revenues. Pin perforations are also uncommon. They are found on some state revenues and on some foreign stamps. They look like a string of little pin pricks, which is what they are. Pin perforations are uncommon because they don't do a great job of making the stamps easier to separate.
Roulettes come in many shapes.
The pictures in the front part of any Scott catalog pretty well show the differences. The most common roulette is the hyphen roulette, which, as mentioned before, is just a line of dash-shaped cuts. Roulettes don't work as well as regular perforations do, but they are cheaper to apply. The roulettes are just added to the paper in a printing press using sections of knife-like printing bars. This results in the perforation holes not being in the same place at the corners of the stamps.