Two plumbing proposals can look different because they cover different access assumptions, diagnostic steps, materials, permit coordination, restoration, or follow-up responsibilities.
Before comparing, put each proposal into the same frame: system and location, work included, work excluded, parts or equipment, access or opening, testing, cleanup, permit responsibility, and what happens if the confirmed condition differs.
A lower first number is not automatically the better fit if it leaves out required access, reconnection, testing, or restoration. A higher number is not automatically justified without a clear scope. Ask for the difference in plain language and get the final scope in writing.
Leak detection, pipe leak repair, and wall and ceiling leak repair can begin with different questions even when the visible symptom looks similar.