Both made by Imperial Glass
Hooked on Carnival
Mitchell Steward said it best when he said you have a contemporary Hobstar & Fan if signed IG or the old is Hobstar NuCut (if the IG has not been ground off). That explains it: watch out for contemporary that have had the IG removed.
Catalog page from Imperial Glass showing some Contemporary Carnival Glass
(Notice the second in from the top right)
Example of a paper label used on Contemporary Carnival Glass
Example of the IG used on some Contemporary Carnival Glass