Just to add an example in which you use them differently: In latex, you can divide a document (or a presentation) in several parts, and each part has its own chapters, sections and subsections. So, in this particular case, part is more general. See more about sectioning in latex 

What is the difference between "section" and "part"?
Everyone knows that JPEG2000 can obtain much better compression result than JPEG. The fundamental transform behind JPEG2000 is wavelet while the basic transform in JPEG is DCT. So my question is why wavelet is more suitable for image compression compared to DCT. Thanks. 
