Hi,
I think you can use wizards, code snippets and code completion in Eclipse, also use some generators which are not available in SAPGUI. But technically SAPUI5 application on AS ABAP is the same as BPS (have to be 
).
But don't forget you can also create SAPUI5 applications for HANA in Eclipse....and I think you are unavble to connect to HANA from BSP envinronment in SAPGUI.
Best regards Jiri
