Scales are made up of half and whole steps. A whole step is the move from one full note to another, such as from A to B, or from C# to D#. A half-step does not go entirely to the next note, but only halfway, such as from C to C# or from E# to F. A flat (b) is a half step "behind" the note, such as from C to Cb. A sharp (#) is a half-step "in front" of the note, such as from E to E#. Thus, once you know where the half and whole steps are, it is easy to play any scale.
Major and minor scales are the two most common scales. Major scales are more lively and happy; minor scales have an eerie quality to them. The distinction between your typical major and minor scales are that the minor scale has a half-step at the third note in the scale and the sixth. The major scale has a half-step at the fourth and the last note in the scale. Both major and minor scales have eight notes apiece, but not all scales do.
The diminished scale has nine notes and has a "horror movie" quality about it. The diminished scale is easy to remember, because the half and whole steps alternate. Music in this scale has a tense and stressful sound to it.
The whole note scale is equally easy to remember, because it is all whole steps to create a seven-note scale. This is often seen as the "opposite" of the Diminished scale. It has a free, spacious quality to the music. The whole tone scale has a strongly Romantic tone to it, and it was popular in the 19th century.
Blues and gospel scales are generally minor scales. All blues scales are minor. They have seven notes in all, and they use what is called a "minor third" at the second note. A "minor third" is three half-steps, or a whole step plus a half step. This is only used in minor keys, and it's a staple of the blues. The blues scale has this minor third at the second and sixth notes. The half-steps are the fourth and fifth notes.
The gospel scale is a form of the blues scale, and it contains a minor third at the fifth and last notes. It has half-steps at the third and fourth notes.