In the Vivado project, run the report_io_timing.tcl script to report timing path analysis for each constraint.
In the ISE project, run "Analyze Post-Place & Route Static Timing" under default settings to generate the timing report.
For the setup and hold analysis of each path, the ISE slack and Vivado slack have 0.004/0.005ns or 0.010/0.011ns difference.
This is expected.
The difference comes from the Total System Jitter calculation for input and output paths in the Clock Uncertainty.
In Vivado, Total System Jitter = (SJ2 + SJ2)1/2
In ISE, Total System Jitter = (SJ2)1/2 = SJ
This is because Vivado takes both source and destination into account.
ISE however, only counts the destination for input paths and the source for output
See also (Xilinx Answer 59944)