How does the ID3 Algorithm differ from a generic Decision Tree learning algorithm
The ID3 algorithm is an algorithm for inferring a decision tree: given a training set, it tries to find a decision tree that tends to label a large fraction of the training set accurately.  See, e.g., https://en.wikipedia.org/wiki/ID3_algorithm.

There is no such thing as "the generic decision tree learning algorithm".  There is no such generic algorithm.

There are many algorithms for learning a decision tree.  ID3 is probably the most well-known algorithm for decision tree learning, and the simplest, but there are other algorithms.  Other algorithms include C4.5, CART, and others.