Difference between web projects with pom.xml and web.xml

Question

What is the difference between Java projects having pom.xml and web.xml? Can projects have both these configurations at the same time?

Answer 1

web.xml is an indicator that the project is running in some kind of servlet container (possibly even a full-fledged Java EE container).

pom.xml is an indicator that the project is built using the Maven build system.

Those two things are entirely orthogonal, so any given project can have none, one or both of them.