You might have some luck searching for 'methi' instead of 'fenugreek' leaves. Here, at least, they're more likely to be sold under that name.
There is a difference in flavour, but it is the same basic note, like the difference between leaf and seed coriander. Seeds are much stronger-tasting. But they'd most likely be used differently, each to its best advantage- seeds fried early on in the cooking process, with the other spices, and the more delicately-flavoured leaves added near the end as an accent. So if you have seeds you probably don't *need* leaves for the fenugreek taste, unless you're adding them to something like a raw salad etc. where seeds would be too intense.