Contrails and chemtrails. What's the difference?

Contrails are linear clouds or "condensation trails" consisting of ice particles that are visible behind jet engines, usually at cruising altitudes in the upper atmosphere. Contrails have been a normal effect of jet aviation since the very first days of its existence.

I don't think you need to tell me what chemtrails are.

This short video shows the difference. The trace from the plane disappears after a few minutes, the chemical trails remain in the sky for the whole day, and then spread through the air.