Yes, T1 is 1.544Mbps upstream and downstream throughput. DSL has many different speeds, from 128Kbps to 6Mbps, but DSL had bandwidth, not throughput at that speed, meaning with T1, you are guarenteed to get that speed. Some DSL is known as ADSL, meaning that one speed (usually the downstream) is faster than the upstream.
It depends on what you need the speed for, because T1 is way more expensive.