They are fairly equal on internal spec. The 5 inch J5 has a FHD screen, is much newer and has a removable battery. On the down side the J5 has only 8gb of internal storage (both have sd slots) so you better pray for Android 6.0 as you won't get many apps to transfer fully to the sd card from the user available 4.x. gb
Have a look at the S5 Neo if it's in your area. Despite the name it's quite new too and I like it, but it may be priced too high.