Neodarwinism is only one of theories of evolution.
Neodarwinism is not a different theory from the TOE. It is simply the combination of Darwin's ideas and our modern genetic knowledge. When Darwin first formulated his theories of Descent with Modification, he did not know at all exactly how traits were passed down. In short, he had no idea what the genetics behind evolution were. He only knew that natural selection occurred and selected for certain traits over others, traits that were then passed down the generations through some mechanism. He did not know what this mechanism was. We know his theory, without the mechanism of genetic inheritability considered, as Darwinism.
But beginning with Mendel's studies on pea plants, we began to understand just how traits were passed down, and now, in the 21st century, we know a lot about how genetics works. Now we know the mechanism by which the selected traits described in Darwinism are passed down from parent to offspring. This new understanding of genetic theory combined with Darwin's incomplete ideas about natural selection is collectively known as Neo-Darwinism.
Neo-Darwinism is not a separate theory from the TOE, but is simply a more complete version of Darwinism that makes up the TOE. Does this make sense?