I've used both and noticed no difference. It really depends if you believe rowaphos claims that it has the largest absorption ability of any phosphate product worldwide.
If you have high levels then iron based media's will struggle to really bring it down unless you use lots of it and change frequently. They are really designed to keep levels stable or lower already low concentrations. Lanthanum based liquid phosphate removers are good at lowering high levels quickly but come with some restrictions.