I have two separate tracks with the same musical phrase.  The notes are identical in pitch and length.  In fact, they are identical in all ways.  What's more, the tracks are of a similar width and yet the notes on one track appear to be compressed even though they are the only notes on that track.
 
However the phrase on the first track looks like this:

 
And, the second looks like this:
 

 
Does anyone know where the settings are to give a uniform appearance?

HI:)
 
Alt + (arrow up) - increase all audio and midi tracks
Alt + (arrow down) - decrease aöll audio and midi tracks
 
Alt + Ctrl + (arrow up) - increase selected track
Alt + Ctrl + (arrow down) - decrease selected track
 
Greetz,
Bassman
 

Looks like what was just said...in the View it looks like the vertical scale is different between the two.

Look for the magnifier icons in the lower right side. 

It is worth taking a look at keyboard shortcuts for views and navigation. In addition to ones pre-assigned there are many useful ones which are not. IIRC, the "return view to previous state" is not... that one allows you return to your current view after you have zoomed in to make a micro-edit and is highly useful.

Autozoom is another feature to be aware of (may be your "issue" in the OP), where the focused track will have a different zoom assignment than all other tracks. You can turn that feature on/off to suit your preference.

You adjust the scale of a MIDI track by adjusting the scale located to the left of the MIDI track and to the right of the MIDI header. Using your mouse you can make it larger or smaller. Its a small area between the header and track. 

There is also the track [View] menu operation to "fit MIDI data", and various mouse controls in the separator between the track header and track data on each track that let you slide and scale the MIDI data in the track.