Here's another chemistry lesson for you (because I'm procrastinating about something else):
Starting with sulfur is an element, denoted by the letter S. It can be alone or bound to other elements in a molecule. When you say something has sulfur, you aren't really commenting on what kind of molecule it is in, or whether it's elemental (not bound to anything.)
Thiols are sulfurs connected to a hydrogen and usually a carbon, in this order: -C-S-H. Usually written C-SH (without the dash between the sulfur and the hydrogen.) The C can be part of something else (indicated by the dash before it) and actually, if can be something other than carbon, like nitrogen. My college roomate used to say: "Carbon has four hands. Carbon likes to hold hands." S has two hands (a.k.a. electron orbitals to create bonds with). The S only takes one of C's hands; the other one is taken up by the H. So the carbon is holding on to other things with it's three other hands.
And yes, like @
Gondwanaland says, thiols are reactive. I can't say "more reactive than S" because S can be in any configuration, so it can be more or less reactive, depending on what other chemicals are in the molecule. And also, like she say, some people do have trouble with them, for whatever reason. (Personally, I thought the mercaptides were pretty stable, but chemistry was a LONG time ago: 20 years since teaching and believe me, we didn't do thiols in the high school where I taught; 35 years since studying.)