playing a scale in different key than song

1. Can you play different scales in a song?
2. What is it called when you play a song in a different key?
3. Do scales change with keys?
4. Is key the same as scale in music?

Can you play different scales in a song?

It's not that the key of a song defines what scales you can and can't use, it's that the scales you use define the key of the song. So no, you cannot use different scales and stay in the same key because by definition changing scales changes the key. However, this is the aural reality.

What is it called when you play a song in a different key?

A simple way round this is using a capo. Put it on fret 2, and use your suggested chords of G,D, Em, C. It will put you into the original recorded key. However,because the voicings of each of the chord have now changed, it will sound a little different.

Do scales change with keys?

Songs generally do not change keys, so you would normally play (say) a D scale all the way through the song, not changing around. You can move around the fretboard in the same key, but to do this you need to use the other 4 pentatonic scales shapes. You can't just shift the same shape around.

Is key the same as scale in music?

A very simplistic way to look at it is this: A scale is a defined set of ordered pitches. A key is the use of a scale in actual music. To say that a piece is in the Key of A, would mean that usually most of the notes in the piece would follow the tonal rules of the A Major scale.