Stan, you are correct.
A glider has a high Aspect Ratio wing (long span, small area)
A F104 har a low aspect ratio wing.
The formula for aspect ratio is ;
AR= (Span)^2 / (wing area)
So a long thin wing has a high AR, a short fat one has a low AR
A high AR wing has less vortex and thereby induced drag than a low AR
wing because the "rest" of the wing is further away from the tip so
that the high and low pressure areas at the tip are smaller.
So, the spanwise lift distribution is a significant factor.
Since winglets increase the AR (span), thats one of the reasons they
reduce vortex.
Cheers,
M