IAS 40 INVESTMENT PROPERTY

This standard deals with tangible items of land and building (or part thereof) which are held mainly for capital appreciation or for rental. The purpose of use can be contrasted with IAS 16 Property Plant and Equipment which deals with items whose purpose is production of goods/services or administration.

The concepts in initial recognition are the same as those under IAS 16.
The difference is in the subsequent measurement; instead of cost model and revaluation model (per IAS 16),we now have cost model and fair value model (per IAS 40)

The cost model under the two standards is basically the same; ie cost less accumulated depreciation less impairment losses.
The key difference is between the revaluation model and the fair value model;

Revaluation model
any increases in revaluation are taken to revaluation surplus/reserve account
depreciation is computed based on this revalued amount

Fair value model
there is no revaluation reserve/surplus account. Any changes in fair value are taken immediately to the income statement.
there is no depreciation computed.