Keeping the room in place changes the conversation.
A finish-led update may keep most walls, plumbing, and appliance locations where they are. A wider renovation may move a sink or range, open a wall, add an island, replace flooring through adjacent rooms, update electrical capacity, or rebuild the room around a different circulation pattern. The cost question changes with every one of those decisions.
Describe the version you are comparing: refresh, rework, or rebuild. Then write what stays, what moves, and what is still unknown. This makes it easier to ask why two proposals differ without assuming that one total is automatically more complete.