I know where are splitting hairs, it's not my intent (I really like your helpful posts btw), but for the sake of accuracy, No
Lortab is not a generic for Vicodin, it's a trade name all it's own, just like
Norco, Xodol, and Maxidone (and others) are for
Hydrocodone/APAP products of different strength combinations are. There is one exception, Lortab 5 (5/500) is the same as "Vicodin" (5/500), they (Abbott Laboratories) also make Vicodin HP which is 10/660, the closest "Lortab" in that strength is called Lorcet and is 10/650.
If the doctor wrote the script for Vicodin it would never be filled with Lortab 5 since it's a trade name.
In this case the OP's doctor wrote the script for Lortab 7.5.
I know, anymore the name Vicodin is synonymous for any Hydrocodone product, even though it's wrong, it's joined the lexicon of names like Kleenex, Q-Tips, Linoleum and dozens of other trade names.
Thanks for your interesting post Mitchigan!