Brazil is clearly the larger of the two: about 8,499,400 km² km² against 16,879,701 km² km², roughly 2× at true size. Drag one onto the other on the map above to feel the gap.
Brazil sits in South America, Russia in Europe. On the old Mercator map the latitude gap distorted how large each felt beside the other; at true size the answer is simply 2×.
The old map muddied it further: Mercator inflates Brazil about 1× and Russia about 6.1×, so on a Mercator-style map this pair appears 11.6× apart instead of the true 2×.
Brazil fits 1× into Russia.