These three markings describe a ladder of fire-safety performance in house wiring — each step adds protection on top of the one before.
FR (Flame Retardant): the baseline safety grade. The insulation resists the spread of flame and tends to self-extinguish, so a fault is less likely to start or feed a fire. It is usually built on PVC insulation.
FR-LS (Flame Retardant – Low Smoke): everything FR offers, plus a compound that produces less smoke when it burns — improving visibility along escape routes.
HR-FR-LSH (Heat Resistant – Flame Retardant – Low Smoke & Halogen): the top grade. It adds heat resistance for higher loads and minimises both smoke and toxic, corrosive halogen gas. This is the HR-FR-LSH grade explained in detail separately, and the reasons it matters are covered under why low-smoke cable matters.
In short: all three are flame-retardant; the difference is how much they also control smoke, heat and halogen gas. For most homes, stepping up to FR-LS or HR-FR-LSH is a small cost for a meaningful safety gain. Compare APAR's Shakti FR-PVC, Shakti FR-LSH and Anushakti HR-FR-LSH wires, or see all house wires and cables.