It really comes down to how the software uses the processor.
Here's the Ark comparison:
https://ark.intel.com/content/www/us/en/ark/compare.html?productIds=83359,82765
The memory bandwidth and speed is better on the 1650, but the CPU cache is better on the 2640. The 2640 is also designed to be used in dual-proc boards, hence why it supports QPI and the other one does not (look at the Bus Speed numbers.)
In a real world scenario, the program itself may have a determining factor for which of these two CPUs are the ideal choice, however it is also possible that the observable difference may be negligible.