Is impotence the same as erectile dysfunction?

Yes, the terms mean the same.
Premature ejaculation is often confused with erectile dysfunction. Premature ejaculation is a condition in which the entire process of arousal, erection, ejaculation, and climax occur very rapidly, often in just a few minutes or even seconds, leaving both the sexual partner and the one experiencing premature ejaculation unsatisfied. Premature ejaculation may accompany an erection problem such as ED but is generally treated differently.

Erection problems will usually produce a significant psychological and emotional reaction in most men. This is often described as a pattern of anxiety and stress that can further interfere with normal sexual function. This "performance anxiety" needs to be recognized and addressed by your doctor.