Difference between SAP UI5 and BSP Javascript App

Hi,

I am very newbee on SAP UI5 development platform and trying to learn this platform on both Eclipse and SAP Netweaver sides. But I have a simple question about usage constraints of this platform.

In SAP UI5 we are coding on Eclipse and transfer this application to SAP Netweaver as a BSP application. And also we can write web applications as a BSP on SAP Netweaver with JS libraries and HTML codes without any need of Eclipse.

What is the advantage coding on Eclipse and transfering as a BSP or coding direclty BSP on SAP Netweaver.

Any answer would be appreciated.

Merve.