Impossible to answer without a detailed description of all features and condition.
value depends on overall condition. Pictures help................
10-10000 USD depending on specifics
Same round, different weapon design.
Different makers. The cartridge used is the 9x19.
100-10000 depending on specifics
The 9mm Lugar round is longer than a .380 Caliber, which is also equal to 9mm in diameter. The overall cartridge and the bullet is larger and the case contains more powder. The 9mm Lugar is more powerful. BTW, the .40 cal Smith and Wesson is also called a 10mm. It is only 1mm larger in diameter and a little more powerful than a 9mm Lugar.
None to really speak of. They are, for the most part, one and the same. The 9mm NATO is merely a variant of the 9mm Luger loaded for military specifications.
Brand new about $180.00
Neither one exists, so there are no differences. However, there is a cartridge known as the 9mm Luger. It is chambered by many makers in pistols. Ruger is one of them.
A few hundred to multiple thousands of USD depending on who made it, exact configuration, overall condition, documentation, etc..
Have it examined by a gunsmith.
9 x 19 is the same as "9mm Lugar" +P means the load will reach higher pressures and veloxcity than a standard load.