[lewispollard]

As mentioned, they're the same. Although "dhyana" can be translated as "meditation", it should be pointed out that at least in the yoga tradition, it refers to a specific, deeply focused state of one pointedness, like jhana, rather than being the act of performing a meditation technique itself - which is referred to as "dharana", I believe. So practicing "dharana" leads to "dhyana", in much the same way as particular techniques of concentration lead to "jhana".