I successfully purchased some Bitcoins via Coinbase. Coinbase makes sense to me as it seems like buying a stock like I can via ETrade. I was able to easily link my bank account to coinbase and it seemed very straightforward.
Earlier today, I stumbled up Buttercoin. It describes itself as a Bitcoin Exchange. Later, it mentions that I can link my bank account. How does Coinbase differ from Buttercoin? Or are they two similar but competing services?