suppose for example if nonce is 32 bit then the total possibility of hashing attempts is 2^32 ( 4,294,967,296 ) times only, but why it is mentioned in every article as PH/s or EH/s (1,000,000,000,000,000,000) or even more. so the question is, is network hash rate different from total possible hash (2^32) expected to do by miner ?
I'm not sure if there is any standard for the nonce range. After a bit of digging Geth uses 64 bits: Will miners meet the situation that they can not find the nonce？ and 2^64 is already a lot bigger number.
I'm not sure if you know how the mining actually works, but in any case let me clarify. The aim is to find a hash value which has small enough numerical value. This target numerical value changes between blocks and is called difficulty. So the miners try to find a nonce with which the block's hash has a numerical value below the target difficulty. If blocks start to take too long to mine the target difficulty goes up and it's again easier to to find the right nonce and blocks get faster - and vice versa.
So the hash rate always means how many hashes are tried per second - essentially how many different nonces are tried. Individual hash rate is simply the hash rate a single entity (computer?) produces and network hash rate is the combined hash rate of all miners.
There is no maximum for the network hash rate as in theory everyone can just try the same nonce all the time with lots of computing power - the same applies for individual maximum hash rate. The maximum amount of different nonces depends on the size of the nonce integer, and as mentioned above I'm not sure what is the standard for that. Also each miner chooses which transactions to include in his/her block so the input also changes per miner - therefore different miners using the same nonce get different output.