The distance between notes is referred to as an Interval. When in reference to ascending or descending a scale this is usually measured as either a Tone or a Semitone. One Tone is the same as two frets on a guitar, while a Semitone is one fret. Anything larger than this would be said to be a Tone and a Half then Two Tones, and so forth. Memorizing the patterns of T&S is, I have found, by far the easiest way of committing scales to memory. Rather than having to learn the individual notes, in order, including accidentals, you simply learn a pattern which is moveable around the guitar neck in the same way as a scale pattern in tablature. Rather than sitting and staring at these patterns on your computer screen, my recommendation is copying the order out and putting it above your bed, next to a bathroom mirror, or somewhere else you’re likely to just happen to see it on a daily basis.
One important thing to remember is that the pattern of T&S Is the distance between two notes, rather than having anything to do with the notes themselves.
Below is the pattern of Tones & Semitones for the Major and Minor scales.
As with many musical terms, there are other accepted phrases which mean the same as Tone or Semitone: Whole-Step & Half-Step; Whole-Tone & Half-Tone.