spotted, mottled, patterned, small tiger
彪 centers on a striking visual pattern: spots, mottling, or bold markings, especially on an animal. The 'small tiger' sense is a specific application of that patterned appearance.
彪 combines 虎 (tiger) with 彡, a component often associated with hair, feathers, or decorative patterns. Together they suggest a tiger's stripes or spotted markings.
A tiger 虎 with extra decorative strokes 彡 on its coat: those strokes are the spots and mottled patterns that make a small tiger stand out.
For ヒョウ, picture a hyō (豹, leopard) — another spotted big cat — standing next to the tiger: hyō -> ヒョウ, and both animals share bold patterned coats.