The fundamental difference between eclipsing binaries and ordinary binaries is just the orientation of the orbits with respect to the Earth. If this orientation is such that one star can pass in front of the other, we observe a variation in the total light output of the system from the Earth because of the eclipse.
Unlike for ordinary binaries, the orientation angle of the orbits for an eclipsing binary is rather well determined because there would be no eclipses unless the tilt angle were small. This often allows masses in eclipsing binaries to be determined with more reliability than in ordinary binaries.