A small sample reflects far less light back than a whole wall, so colours often look more intense once applied at scale; a screen additionally renders colour with emitted RGB light rather than reflected pigment, and is affected by that specific screen's calibration and brightness.
Mid-tone, moderately saturated colours tend to shift less dramatically at scale than very pale or very saturated ones.
Pale colours can look flatter, and saturated colours can look noticeably more intense, once applied to a full wall rather than a small chip.
Testing advice
Paint a large sample patch (not a small chip) directly on the wall, and never assume a screen rendering will exactly match the physical result — see methodology.
Lighting simulations and descriptions here are approximations, not exact physical predictions — see methodology.