What is the difference between a chemtrail and a contrail?

Iv'e read the info, but how do you know a chemtrail isn't just a contrail hanging around? I know some belive chemtrails are BS, but for thoes of you who belive they exist....how do you know the difference??

Follow up question If so, Do you live in a cave? Chemtrail Patent Issued/Filed Dates: Aug. 12, 1975 / July 22, 1974 Application Number: US1974000490610 IPC Class: B64D 1/16; Abstract Light scattering pigment powder particles, surface treated to minimize...

Ok, so one day i was running in my neighborhood on a partly cloudy, sunny, warm day and i saw some sort of jet flying overhead, there was a long white trail of thick condensation or chemicals from a "chemtrail" behind it. I stopped running...

I have always been skeptical about the existence of chem trails. Some of the images I have seen just look like natural cloud formations. Other images of obvious jet trails I just have never seen. Until this morning. I was out walking my dog at the local...

Some people have floated the idea of putting up a donation website to collect money to finance a plane to collect air directly from a contrail/chemtrail to have it definitively tested. People involved are from both sides of the "chemtrails"...

One question I have that I cannot get answered. Regarding the chemtrail debate, why is it that only fighter jets leave persistent trails? Why is it that 2 visibly identical jets fly back and forth over my town,where one leaves a normal dissipating contrail...

There are many sources that dispute the fact that our skies are being spread with chemicals, and that governments of all the countries involved won't admit that this is happening. Some are trying to debunk this fact claiming that they are only condensation...