Compounds are essentially the amalgamation of different elements in which the separation of said elements would be difficult. Additionally, when compounds occur, energy can be given off or absorbed, unlike mixtures.
Mixtures are essentially an amalgamation of different elements in which no chemical reaction occurred. This is the key difference between compounds and mixtures, in addition to the fact that it is easy to separate a mixture into its individual parts.
More information can be found at the following link:
Hope this helps!