Hello,
E1 and T1 circuits are considered leased lines, while Frame Relay is not. The difference is that with a leased line, the bandwidth is always available and only for you, whereas with Frame Relay, the bandwidth is in a certain way statistically shared, and the connection is set up through a series of switches. Leased Lines are therefore usually more expensive and limited with regard to distance; Frame Relay circuits are usually cheaper and cover a wider distance.
HTH,
Georg