This is a really good question considering that these are the only functions (within Data Echo) that can be used to initiate data exports, but there are certainly some notable differences.
Foreground and background execution
Data Snap: background only
Export Control: foreground or background
Best practice tip: execute in background to avoid having the process time out
Data volume limitations
Data Snap: data volumes are limited
Gold Client is delivered with this parameter defaulted to 1,000 records but it is configurable and so customers can edit as needed. Note: this limitation is only applied to the top level object and has no bearing on any related/dependent data objects that are included in the export.
Best practice tip: 1000 is recommended as it is typically large enough for users to be able to export their data while not being a performance burden on the team's production system