A major scale in western music is very similar to the bilawal raaga in Indian classical music.. All the notes used in this scale are major which means "shuddha swara"in indian music.. In terms of feel, the major scale gives out a happy and bright feel..the seperation between the notes in a major scale is fixed and constant..
In western music we call it --- TONE TONE SEMITONE TONE TONE TONE SEMITONE
We also call it ---WHOLESTEP WHOLESTEP HALFSTEP WHOLESTEP WHOLESTEP WHOLESTEP HALFSTEP
TONE or WHOLESTEP means when two notes are seperated by another note in between. for example C and D is seperated by a note higher than C but lower than D which we call C#(c sharp) or Db(d flat).. So we can say C & D are wholestep or tone apart..similarly D & E, F & G, G & A, A & B are all wholestep or tone apart because again there is D# or Eb between D & E, F# or Gb between F & G and likewise.
Exceptions:--- Between B & C and Between E & F there are no notes..or we can say that B# or Cb and E# orFb doesnt exist... SO we can say that B & C is semitone apart or halfstep apart..Similarly E & F is also semitone or half step apart.
Easiest scale to learn is C major scale as all the notes in a C major scale are natural(without any sharps or flats)So C majopr scale will look like
Degrees of scale-- 1 2 3 4 5 6 7 8
Notes of C major-- C D E F G A B C
So its clearly evident that 3rd 4th & 7th 8th notes of a major scale are semitone or halfstep apart...
And thats the general rule of any major scale...