Lots of differences Sambo!
The LP Junior has a thicker body, wrap around bridge and comes in 2 flavours (Single and Double cutaway). The different colours also had different model names (TV for the limed mahogany finish), and the 2 pickup versions are called specials.
The original Melody Makers had single coil pickups which looked a bit like EMG's - black with no poles. The were single cut, but with about 25% less body depth than a junior. All the controls were on the pickguard, and they came in 1 and 2 pickup versions. They had a wrap around too. The double cutaway came later, but looked much the same other than some of them got a maestro tremelo. The final incarnation had them looking like SG's with still the same single coil pickups apart from the one pickup version, which got a P-90, just like the SG junior. The easy way to tell Melody Makers is to look at the headstock. They have a narrower, parallel sided headstock through all the years. The picture is an original single pickup, single cutaway.
Your guitar looks like the LP Junior, but with a stop tailpiece and tune-o-matic bridge, but still the narrow headstock. Musiciansfriend are selling them for $529
http://www.musiciansfriend.com/product/Guitar/Electric?sku=517842and they sell the junior for $649
http://www.musiciansfriend.com/product/Guitar/Electric?sku=517341
