What is the difference in tramadol and tramadol hcl?

no difference

Tramadol HCL - it's Tramadol Hydrochloride - the full name of the drug..

HCl is simply Hydrochloric acid, it is used to aid the absorption of medications & is found in most pills. As for APAP, that's just a term for acetaminophen(Tylenol) that is used in conjunction...

Yes, it's the same but have a different dosage for people and dogs.

yes