These are the main types of conflict:
A typical conflict is when file content is in conflict requiring an invocation of the file merge tool.
A less common conflict is when actions conflict but not file content, for example, when the file was modified locally but deleted in the repository, or the file was renamed from "a" to "b" locally, but from "a" to "c" in the repository. In such cases, merge may not be possible, and you need to decide which change to accept, use local or use repository.
The Synchronize wizard recognizes certain situations that are identified as pseudo-conflicts. For example, two users may have independently deleted the same file or created the same folder. You may want to investigate such situations, but if you accept them in the Synchronize wizard, the metadata will be updated so that they do not subsequently appear again.