Similar. Carisoprodol, a muscle relaxant, is used with rest, physical therapy, and other measures to relax muscles and relieve pain and discomfort caused by strains, sprains, and other muscle injuries. Orphenadrine is used with rest, physical therapy, and other measures to relieve pain and discomfort caused by strains, sprains, and other muscle injuries.
Different meds. They are different medications. Both are listed as "muscle relaxants" but they are really both mild sedatives. One is an antihistamine and one metabolizes to a drug called Meprobamate which is a barbituate medication. As far as their effectiveness that is harder to say. One may work well for one person and the other may not work or cause side effects and vice versa. Not my favorite medications.
See below. They are both characterized as muscle relaxants but in truth they both have a sedating effect and probably cause relaxation through that effect, not for their direct effect on muscles. They are completely different chemically and have different breakdown products in the body.