Apex lite vs jr
 

What can't the junior do that the lite can?

Just get the lite

If you go to page 6 of the manual, it gives you a nice comparison of the capabilities.
http://www.neptunesystems.com/wp-con...nce-Manual.pdf

I have both the full Apex, and the Apex Jr, with one display. The extra Jr gave me another temp probe and extra outlets.

I have both there's nothing one can do that the other can't. The jr is just striped down light and the light is a stripped down apex full. All it does is lower your entery cost. If u wanted the jr to do everything the light dos it would cost u more in the end that just buying the light.