Until they detect orbital motion around each other, you can't necessarily tell if a particular pair of stars is an "Optical Double," which means that they are simply a line-of-sight double, or a "Physical Binary," which means that they're indeed orbiting each other.
Astronomers classify physical binary stars depending on how they are detected. Some (perhaps not all of these) are...
*Visual Binary - Close enough to resolve individually and detect orbital motion over time.
*Spectroscopic Binary - Orbital motion is revealed by periodic Doppler shifts of the spectral lines, but the individual stars can't be resolved.
*Eclipsing Binary - Usually an unresolved pair, but as they orbit each other one (or both) of the pair occults the other as they orbit. The presence of two stars can be deduced by a careful monitoring of the light curve they produce. Most eclipsing binaries are actually eclipsing-spectroscopic binaries, in which both Doppler shifts and occultations can be detected.
*Also there's a "Spectrum Binary" - which is a rare type where spectral lines show that there are two different temperatures of star, but no other movement is detected. Often these type "graduate" into one of the other more common types once motion can be deduced. Note that a spectrum binary can't necessarily be proven to be an optical double or a visual binary since line-oif-sight could also explain the phenomena.
The whole universe seems to work like a fine watch, amazing isn't it!
Absolutely! My favorite hobby is heading out to the Mojave on New Moon Saturday nights and hang out with my friends and our telescopes. The most beautiful cathedral I've ever known! :)