Difference Between transistors.. Noob Question

Is a “2N3904” Transistor the same as a “N3904”
what effect is the 2?

Never heard of an N3904. A 2N3904 is pretty common though.

2N means there are two junctions (NP or PN junctions within the device) It also usually implies there are 3 leads on it. (So 1N means 1 junction, which is typical for diodes.)

3904, 2222, etc are the part number. When you look it up the specs or find the data sheet, this will tell you the type (NPN or PNP), the current, voltage and response time characteristics of the device.

Often markings on devices are shorthand versions of the full datasheet number, so yes dropping the 2 isn’t unusual. Japanese transistors usually have the 2S missing (so A472 means 2SA472 etc).

The number is always the lead count minus one. Nothing to do with junctions! A 3-lead unijunction transistor is a 2N device for instance. A small signal MOSFET with 4 leads (gate/drain/source/substrate) is 3N…

There’s never any reason to print the number since you can count the leads!