Step 1: Compare on carrying capacity.
Because its track is wider, broad gauge can support heavier coaches and higher speeds, which is why it now carries most of India's passenger and freight traffic.
Step 2: Compare on where each is used.
Metre gauge, being narrower and cheaper to build, was laid mostly on hill and low-density branch routes where traffic did not justify the cost of broad gauge.
Final Answer:
The key difference is track width and capacity: broad gauge is wider and carries the bulk of traffic, metre gauge is narrower and limited to lighter routes.$\boxed{\text{Width and capacity differ: 1.676 m vs 1 m}}$