I believe you are asking multiple questions here.
Q) Can Hardware Inventory be run at a specific time every day?
A) Yes, in the console, Site Settings, Client Agents, Hardware Inventory, for Inventory Sechedule you would like a "full schedule, of daily, at the specific time you indicate." Personally, I'd leave it at simply, daily. But that's just me.
Q) Can a comparison be made between Current Hardware Inventory and Historical Hardware Inventory?
A) Yes, the SMS database will have current and (limited) historical hardware information. If you are looking at the views when you create a report via the console, you might notice some views start with v_gs and v_hs; v_gs is the current, v_hs is historical. Note not every computer will have historical information--if nothing has changed for that particular inventory, there won't be anything historical.
Q) Automatically notify someone about changes to hardware inventory.
A) I don't have a concrete, "here's how", answer. Just a direction. Although I've never done this, this sounds like if you had an SQL wizard/guru, they could schedule tasks to run the reports you want. I have no idea if they'd be able to schedule emails or something based on the report results.
You don't mention what/why you are monitoring for changes.
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