What is the difference between XRD and EDX techniques?

They are fundamentally different characterization methods. Basically XRD attempts to characterize the material by analyzing the crystal structure, and comparing it against a database of known structures. Pros: Based on the instrument and the sample, it can provide you with loads of information about the material, such as phase, grain size, texture, %crystallinty , and stress. Cons: It's toothless against amorphous materials. You need to have a general idea about the possible composition of the material. Approaching an absolutely unknown sample with XRD alone may be confusing. EDS is an elemental analysis technique. Here you stimulate your sample by electrons or high-energy photons, and detect the spectrum of outgoing photons. Pros: This is an elemental analysis technique. Compared to XRD it requires very little expertise in materials science, and less initial information about the sample. It is usually combined with scanning electron microscopy, which makes it a versatile tool for acquiring a composition map of the sample, or getting area-specific elemental analysis. Cons: It suffers from numerous artifacts, which any good operator should know about. Some are general artifacts, and some are specific of the machine in use. It has a poor spectral resolution, compared to its cousin, WDS. It also suffers from a poor spatial resolution.