Three right angled triangles are all that is needed to create one of these Flying Geese units (or patches.) The largest triangle piece is considered to be the "geese" piece -- (why it is not called a "goose" piece is beyond me). The other two identical triangles are considered to be the "sky" pieces.
Flying geese units are probably the third most commonly used patches in quiltmaking -- following the square and the half square triangle.
Nine Patch Square - Variation
Free Quilt Block Pattern
The 9 Patch Square - Variation quilt block is built on the Nine Patch Square -- a logical assumption. The difference between the two blocks is that the centre in the Variation version has a four patch unit rather than a single square.
In any case, both quilt blocks are effective as evidenced by the illustrated quilts. No difficult patches to make -- just colour choices can make all the difference in the end result.
Related - Nine Patch Square