A counter (price-computing) scale is built for billing small quantities fast. A platform scale is built for heavy, bulky goods. Many shopkeepers actually need both.
Choose a counter scale if
You bill by weight at the till — meat, grains, sweets, general goods up to ~40 kg.
Choose a platform scale if
You weigh sacks, drums or bulk goods from 100 kg upward.
The dual-purpose answer
A counter billing display paired with a 100–150 kg platform lets you do 'counter sale bhi aur aata ki bori bhi' — one setup, both jobs.