Oppose means to face something or somebody else in disagreement. It can be used to describe the physical location of items or disagreeing ideas.
A. "The table and chair are opposed to one another."
B. "The workers are opposed to the new development."
Appose on the other hand means to juxtapose or place side by side. This word is rarely used except for specific required contexts.
"The guns were apposed before being placed into their casings."