To make matters worse, sometimes several different names are used to specify the same number. A set of orbital elements is a snapshot, at a particular time, of the orbit of a satellite. Epoch is simply a number which specifies the time at which the snapshot was taken. The orbit ellipse lies in a plane known as the orbital plane. The orbital plane always goes thru the center of the earth, but may be tilted any angle relative to the equator.
Inclination is the angle between the orbital plane and the equatorial plane.
By convention, inclination is a number between 0 and 180 degrees. Two numbers orient the orbital plane in space. The first number was Inclination. This is the second. After we've specified inclination, there are still an infinite number of orbital planes possible.