Symmetry in interiors usually means bilateral symmetry — pairs of objects flanking a central element. A fireplace with matching armchairs on either side. A bed with matching nightstands and matching lamps. A console with matching mirrors above. The eye reads symmetry as ordered and formal; it's why traditional and classical interiors lean heavily on it.
Asymmetry — intentional non-mirroring — feels more casual and contemporary. A sofa balanced by a lounge chair plus a side table (not mirroring). A bed with a nightstand on one side and a tall floor lamp on the other (different objects, similar visual weight). Modernist and contemporary interiors often use asymmetry to feel less stiff.
Neither is better — they signal different moods. The mistake is mixing them randomly. A room with a perfectly symmetrical fireplace wall and chaotic furniture placement reads as confused. Pick a stance per zone and commit.