Following if a part of theory which i read in one tutorial by "Dennis" - The Bhangra King.
Perfect Intervals:

Lets take a Cmajor scale=
(- indicates a half step,i.e a jump from say Cto C# or E to F)
The 1st note C is the root.
The 8th note which again is C is called the Octave.

The Root,4th,5th and the Octave are our Perfect Intervals.
The 4th note is called the Perfect Fourth and the 5th note is called the Perfect Fifth(ie. Perfect 4th w.r.t our root which is C in this case)

Now before this i had read one missing fret tehcnique by "amit82cse". In that technique he had mentioned that once we find the scale ( using wwhwww style ) we need to convert the chords in the pattern of Major minor minor Major Major minor Dimnished.
so if the scale of C is C D E F G A B, then using the Major minor thingy, the scale should come out to be C Dm Em F G Am Bdimnished.

Question: How can there be two scales for a same key note. If not, then which one is the correct ? And if both are correct using different music patterns then can someone explain it to me.

Thanx to all those who's made this wonderful site.
Cheers to all.