In _data mining_, we can use _machine learning_ (ML) (with the help of unsupervised learning algorithms) to recognize patterns.

_Pattern recognition_ is a process of recognizing patterns such as images or speech. We can recognise patterns using ML. For example, once a neural net is trained, using ML algorithms, it can be used for pattern recognition. Other methods, even ones not related to ML and data mining, can be used for pattern recognition, such as a fully handcrafted pattern recognition system.

In general, 

1. data mining is mostly associated with statisticians, 
2. ML is mostly associated with computer scientists whereas,
3. pattern recognition is mostly associated with engineers.