Isolation & Power Transformers

A power transformer is rated for continuous operation. Power transformers can be operated continuously for days and even months without being shut down.
I don't think isolation transformers can run for so long. They would be rated for short time operation.

Also isolation transformers usually have 1:1 turn ratio. They are used for isolating the secondary from the primary.
A power transformer is used for stepping up the voltage generated in the power plant before it is transmitted to the receiving station. Usually power transformers are 11kV/132kV or even higher. Higher the voltage, more is the transmission efficiency through a transmission line. At the receiving station, it is stepped up to an even higher voltage if required.

Power transformers are rated at tens of MW. I don't think isolation transformers have such high ratings.

Power transformers usually cost crores of rupees.

I saw these in some links But the level of isolation in both are the same right Then why is the difference

Other than unity turn's ratio there seems no more difference between the two

Cost is a very big difference.
I do not know exactly about the internals of a power transformer, but I think they are made in such a way that the heat can be dissipated easily.
The material used for making the core is different I think. While power transformers use CRGO steel (pretty costly), an isolation transformer may use cheaper quality material.

Power and isolation are just two types of a transformer.
Hatchback, sedan, truck, bus - all of these are different types of cars.
Would you buy a truck for your daily commuting needs?
Similarly you will use either a power or an isolation transformer as per your requirement.

As far as i know the difference comes in the usage.

Power transformers as you know is used to step up the voltage to a very higher value to reduce loses.

Isolation transformer is mostly used for safety purposes, you do have a transformer (Isolation) for which the primary is connected to ground and also connected to source, the secondary is connected to the circuit or other electrical equipment, this helps in eliminating the shocks if we have any fault voltage at the primary end.

The main application is to save the circuit in the secondary!

I think an another difference is about size. Isolation transformers are usually used in electronics (high freq.) but power transformers are frequently used in power transmission (low freq) applications. Here the difference is frequency. As you know when frequency increases, the size of the transformer decreases.