Before going to the differences
Know what exactly is Machine Learning?
In simple words, Machine Learning is an application of Artificial Intelligence that makes the system to automatically learn and improve from the experience without being explicitly programmed. Machine learning can access the data and use it to learn themselves.
What exactly is Artificial Intelligence?
AI is a subfield of computer science and it is concerned with solving problems that are easy for humans but not for computers. AI can do anything that a human can. AI includes all kinds of tasks like recognizing objects and sounds, speaking, translating, etc.
What exactly is NLP?
Natural Language Processing is a branch of AI that can generate the language that humans can in order to interface with the computer in both written and spoken contexts using natural human languages instead of computer languages.
AI can cover anything that can make a machine smart. It can be a car, a washing machine, a motorcycle, etc.
ML is commonly used with AI but not the same. ML can make the system smarter and smarter over time without human intervention by learning themselves.
Deep Learning (DL) is ML but applied to large data sets. Most AI work now involves ML because intelligent behavior requires considerable knowledge, and learning is the easiest way to get that knowledge.
Automated Speech Recognition is the processing of speech to text whereas NLP is the processing of the text to understand the meaning. Because humans speak with colloquialisms(a word that is not formal) and abbreviations it takes extensive computer analysis of natural language to drive accurate outputs.
I hope you got a clear visual over AI, ML, and NLP.