I'm assuming that odorless mineral spirits are safe to breath but I'd like to know for sure. Are the fumes still toxic though the mineral spirits are odorless?
Also, are odorless mineral spirits weaker and less effective than regular mineral spirits? Are they diluted compared to regular mineral spirits?
In short, yes there are still harmful (the can should say what the hazards are). The big advantage is that they don't stink up the whole house. I am not sure but while they are harmful they may not be as harmful as those that have odor. Basically, anything that is a solvent (including ethanol which fuels many people through one of its common forms like beer) is harmful. Just different ones having varying degrees of harm.
I have used odorless mineral spirits for years and I have not noticed any performance difference from those with odor. Just make sure you at least open a nearby window when working with them, preferebly with an exhaust fan running if you can (a standard house fan pointing out the window will work).