Triads are built in 3rds. Blue Lawnchairs:A Triad is a Type of ChordC-E-G is a triad|-------||-------||-0----||-2----||-3----||-------|A chord is any 3+ notes played harmonized
That's a rather vague question, but I'll say that specific chords are made of specific notes, and different chords are made up of different notes. from a listener's perspective, it doesn't matter...
A major chord is just a triad (3 notes, the 1st being 3 whole steps away from the 2nd, and the 2nd being 3 whole steps way from the 3rd). For example a major C chord consists of the notes C E and G....