SIMPLY u have 2 type of speakers......... Coaxials and Components
Coaxials: u can get these in round shapes or oval shapes.... sizes are 4",6",6.5",5.25",6x9",5x8",7x10" etc
in a coaxial ur tweeter/tweeter's are mounted on top of the woofer (or midbass driver). meaning where ever ur installing ur speaker, the vocls and mids will be coming from that area.
eg of 2-way coaxial speakers of different shapes and sizes
eq of 3-way coaxial speakers
the same way u have 4-way, 5-way coaxial speakers.
Components: these are mostly round.the tweeter and midbass driver are separate. meaning while u install ur speaker in the lower part of ur door, u can install the tweeter anywhere u like depending on where u wanna hear the vocals coming from and what suits u.
2-way component speakers with crossover (the boxy thing with the speaker and tweeter in the pics. see how it works)
eg of 3-way component Speakers