What is the main difference between AST and JDT Java model?

Question

What their advantages and disadvantages if they used to analyze the code?

Answer 1

The JDT Java model is much higher level: it gives a structure of your project, but is limited (roughly) to definitions: packages, classes, fields, methods.

The AST is much lower level. It represents the source code faithfully, including method bodies.

The Java model is usually very fast to access, while the AST requires full Java parsing and is slower.