whats the difference between regular brass track and euro brass track?
This distinction applies mostly (or maybe 'only') to Aristocraft Track.
With 'Euro' (also called 'Narrow Gauge') track, the ties are large - 3/8ths of an inch long, and spaced 5/8ths of an inch apart. This represents both the larger scale of 'narrow gauge' equipment and the fact that ties are spaced further apart on European railroads than they are in the US.
'Regular' track, the ties are 1/4 inch across and spaced 1/2 inch apart to be more in scale with standard gauge US track.
I think you can also tell by counting ties per foot euro is 12 and american is 14 ties per foot
Nm-Jeff