Q.  Are Neanderthals a different species to humans?

A.  No. All humans can potentially interbreed, and so belong to the same species.

Q.  You're saying that Homo sapiens, Homo neanderthalensis, and predecessors such as Homo habilis are really just races of man?

A.  Yes, but it is better to call them "Landraces", and use the double-quote designation, such as Homo "Sapiens", Homo "Neanderthal", and Homo "Flores".

Q.  So what distinguishes one human landrace from another?

A.  If you imagine all present and past human genomes spread out over a flat plane, different landraces just have different clumps selected from the whole.

Q.  And different "landraces" may have overlapping clumps?

A.  Yes. It's the observer who decides where to draw the clump boundaries, there are no inherent divisions over the plane.

Q.  Where can more be found on this?

A.  See The Truth About Human Species.