Calendered vinyl is for short term use . . where most of the time the vinyl will be inside not exposed to the sun. Also, known as intermediate vinyl.
Cast vinyl is a little more expensive but it will last longer usually for vehicle graphics, window lettering. etc. etc.
Decent vinyl will be from Oracal (Cal+), if I am not in a rush I will usually order my vinyl from Fellers.com these came out with their line of Shine Brite and it has worked out great for me.
Cast vs. Calendered Vinyl
read this articel it will give your in depth read about cast vinyl v. calendered vinyl.