Scotia is a synonym of trochilus.

In architecture terms the difference between trochilus and scotia

is that trochilus is an annular moulding whose section is concave, like the edge of a pulley; a scotia while scotia is a concave molding with a lower edge projecting beyond the top.

As nouns the difference between trochilus and scotia

is that trochilus is any member of the hummingbird genus Trochilus while scotia is a concave molding with a lower edge projecting beyond the top.