Both are 4K; the 65" gives a more immersive experience if you have the space and viewing distance (roughly 8–10 ft). A 55" fits smaller rooms and is often enough for typical living rooms. Choose 65" for a dedicated media room; 55" for flexible spaces.
Physical Size Comparison
Relative physical size of each display at scale (same units as your selection).
55" 4K TV
65" 4K TV
55" 4K TV
in
DIAG55.0 in
W×H47.9 × 27.0 in
cm
DIAG139.7 cm
W×H121.8 × 68.5 cm
65" 4K TV
in
DIAG65.0 in
W×H56.7 × 31.9 in
cm
DIAG165.1 cm
W×H143.9 × 80.9 cm
Pixel Workspace Comparison
Effective pixel workspace with 1x/2x scaling. Shows how much logical space you get on each display.