For example housing act 1988 has schedule 2. But what is a schedule and what differentiates it from a section or a chapter or an annex?
A statutory schedule is an addendum to a duly enacted law that is included in the law itself, even though its contents are more similar to what would usually be found in a regulation.
This stylistic device allows the language of the main statute itself to describe the content of the law briefly and in a readable fashion, while putting specific details, often details that vary by time period or product regulated or location, in an appendix that can be perused once one has groked the primary statute itself. It also allows for statutory amendments to be made to the details in the schedule without amending the core statute, which can be helpful for people trying to work out the legislative history of the statute.
Schedules are common in lists of fees that are amended from time to time by statute, in laws that implement treaties that are themselves structured that way, in laws establishing customs duties or excise taxes, in laws that are phased in over time, and in laws where the legislative process reaches a consensus on the main structure of the statute which is drafted at that time before a consensus is reached on the specific details of some of its "moving parts".