typical overuse of buzz words to get as many hits as poss lol.
the way to tell the difference for the uninitiated is the size, shrink tube typically comes in aprox 50mm lengths of varying diameters in a card backed bubble like such,,
and silicone rig tube in 2.5 - 3 mtr lengths like this
please note, i do not in any way endorse ESP products, the use of such was purely incidental (tho they do have some REALLY cracking stuff out there)