A machine learning backend is the part of the machine learning software that runs the algorithms. The backend does not need to be installed on your machine. The backend is responsible for running the algorithm, providing feedback on the results, and storing the training data.
Machine learning is an application of artificial intelligence that involves algorithms and data that automatically analyse and make decision by itself without human intervention.
Artificial intelligence is a branch of computer science that aims to create intelligent machines. These machines are capable for performing tasks that requires human intelligence.