The four places the difference usually hides
Frequency is the first: one quote assumes three attendances a week and another assumes five, and neither says so prominently. Periodic work is the second, since a proposal excluding floor treatment and high-level dusting looks considerably cheaper until those items are needed. Consumables are the third, and they can represent a meaningful sum over a year. Excluded areas are the fourth and the least visible.
Checking those four accounts for most of the variance between proposals. A quote that appears twenty per cent lower frequently turns out to cover four attendances rather than five, exclude all periodic work, and assume the client supplies consumables. None of that is dishonest. It simply means the two documents are describing different arrangements and cannot be compared on price alone. The remedy is not suspicion of the cheaper proposal but a common scope that makes the two describe the same thing.
