The taste is completely different. I think you're referring to methi leaves, which can be bought at any Asian/Caribbean shop. Curry powder can taste of anything, really, as it's just a mixture of different 'curry' spices. A good supermarket also should have them. If you do mean methi leaves, the taste is superb and I can think of nothing else that compares. They can lift the most boring curry and make it taste special. Methi leaves, by the way, are the leaves of the fenugreek plant, and taste different to the seeds.