Scott,
White spirit works better than the 'stuff you buy' because it is 100% active ingredient.
A gel will contain a thickener like a cellulose or gum plus a perfume .If you want sweet smelling white spirit use it , if you just want to get rid of tar , grease etc then use white spirit.
Ecospotter is isopropanol mixed with MS which will not be as effective as white spirit on tar and will cost much more.
Cheers
Doug