Data Mining is applied Machine Learning. The former focuses more on the practical aspects of deploying machine learning algorithms on large datasets, whereas the later focuses on modeling, prediction, classification and computational efficiency for large datasets. Also, please check the following question in RG with lots of good answers.
In machine learning ,we hear about supervised learning,unsupervised learning and semi- supervised learning.In data mining ,we learn few techniques such as classification,association,and clustering. As per my knowledge,while introducing these classification ,association and clustering techniques to students ,will link these concepts to supervised and unsupervised learning techniques.so in data mining few concepts are inherited from machine learning
You can look at CRISP-DM methodology (Cross-Industry Standard Process for Data Mining). Data mining is a few-stage process. Machine learning special algorithms and methods that are used in one step of this process - modeling (see Fig 3. - table of tasks during Data Mining here http://www.dataprix.net/en/reference-model-crisp-dm )
If you use weka you will have to convert data file into arff format. With R, csv file can be used directly. R has very good functions for visualization of associations rule. Documentation of the package "arules" is available.
With simple function interface, It is easier to use than weka GUI.