Tier2Gen Visa fee - does it varies for different Applications

[abhjieet4u]

Hi,

I have just filled a Tier 2 General Visa application and paid around INR 76368 (GBP 860) including Priority service (decision in 5 working days), today I found that just a day before, my friend has paid only INR 62935.00 (GBP 710) for the similar role and same priority service application (for the same employer). The only difference is the Visa centre which is located in different cities. There is a significant difference in IHS fee as well, I paid INR 110,412 (GBP 1245) and my friend has paid around INR 102,000 (1150). Now I have the following questions:

1. The difference in fee is significant for both IHS fee and Visa fee (exchange rate was stable in these two days), so I would like to understand the items things which decide the fee?
2. The Priority service fee on Gov.uk site is 500 GBP but the fee charged for Visa with Priority service is around INR 76368 (860 GBP) which includes both Visa fee (610?) and Priority service fee, I am unable to understand this calculation. Can some please help me with this calculation?

I am just worried that I or my friend has not filled something incorrectly I application which can create a problem in Visa Approval.

Thanks,
Abhijeet