IMO D1, D2, D3, JUCO, and NAIA are all the same route, but have different stops.
An example of a different route would be "club baseball"
The more people attempt to isolate, defend, or promote the differences between those designations, the more segregated they become. Bottom line they are all baseball players and if you have the tools, the professionals paid to seek you out will find you. In the mean time enjoy the opportunity to play the game.