I have multiple audio "tracks", one louder than the other, one quieter than the other. Is there something I can do to make all have the exact same amount of volume?
Have you tried selecting Audio Console (View/Windows) and then adjust the track audio levels by the faders?
Alternatively, the audio level of each track can be adjusted by the fader at each audio track's header. Also, each audio event's level can be adjusted down by the pull-down bar on the audio event, or increased via the MAGIX audio FX Volume plugin.
Additionally there are track volume envelopes can be applied as well as event normalization..though normalization may or may not help based on an event's highest peak. A compressor/limiter plug-in on a event, track or sub-master is an option as well. A comp/limiter on the master bus can help with overall leveling too. All of the above can be dangerous if you don't know what your doing though.
One simple way to do this would be to make use of the Tool Generate Loudness Log. Run this tool for each audio track with the remaining tracks muted. You'll have to write down the Integrated LUFS values since the file is overwritten each time it is executed. You can then adjust track volumes. Not the best approach, but it is simple and quick and will get you "in the ball park".
I have not tried it but The Levelator may be of interest. It is a stand alone app that evens out volume differences. You could render a PCM (.wav or .aif) run it though the Levelator, and import the file back into Vegas.. or trans-code it to the needed audio format and mux into the rendered video.