The half square triangle unit is probably the most commonly used patch in a quilt block -- well it is second only to the square. It is made simply with two triangles, filling up half the square each -- hence the name. Take a quick look through this website, or in any quilting magazine, and you will start to notice that this half square triangle, regardless of its size, is present in more quilts than not.
Free Quilt Block Pattern
The Triple Star quilt block looks more like a pinwheel block to me. However, I imagine that the name comes from the fact that everything but the background fabric seems to form a type of "star".
Although this quilt block might look challenging, it really is not. The method of construction is what makes it look difficult, at first glance. Groups of quilt patches are created and then those groups are sewn together into diagonal rows, rather than the usual straight across rows. This is a fun block to make, so don't be shy to give it a try.
The sample quilt layouts show both quilts with blocks laid out on point. However, by simply changing up the background colours you get two totally different looks.