What is the difference between "Java Build Path" and "Deployment assembly" in Eclipse dynamic web project IDE?

Question

I see these two options in dynamic web project in Eclipse IDE.

I have been working for a year in Eclipse IDE, but still couldn't get a clear difference between Java Build Path and Deployment assembly,

because when I encounter a problem some answers suggest me to add jars to Deployment Assembly (I do that and it works) and some recommends to add things to "Java Build path" and it works. Some say restart eclipse and things work.

I would really like to understand the difference and learn. Please help.

Answer 1

when you have suggestions to add some jars to build path it means they are needed for compiling and runtime, in the other case your code will be available only for compiling because eclipse won't create those jars unless you put them in the server's library folder (and this is the manual way of deployment assembly)