I gave XAT Mock 1 and got 88%ile, is XAT paper on similar level or tougher than XAT mock 1 paper ?

The sample size of these mocks is very small as hardly 300-500 students are writing the mocks. So, the percentile won't be indicative of your percentile in the actual XAT exam. The purpose of these mocks is to finalize your strategy for the actual XAT and also work on the accuracy. Anyways, if you are getting 28+ in cracku mocks, it will be a good score as quant in these mocks is very difficult. Someone scoring 28-30 marks in these mocks can score 35+ in the actual XAT exam

Prepare for the worst, Hope for the best