This is an example of intarsia:
It's just using two or more different yarns to create a picture.
This is entrelac:
The diamonds are knit one at a time- the black ones are knit slanting to the right, then stitches are picked up along the left sides with white yarn and the white diamonds are knitted slanting to the left.
Intarsia is knit (generally) in straight rows back and forth across the piece, changing yarns to create the picture.
Entrelac is knit one triangle or diamond at a time, with each new triangle/diamond building on previous ones.