These systems solve different problems. Start with the workflow that is failing, then choose the smallest system boundary that fixes it.
A point-of-sale system focuses on selling: products, prices, discounts, payment methods, receipts, cashier activity and stock impact. It may include customer and inventory features, but its centre of gravity is the sale.
If the main problem is slow checkout, inconsistent pricing or poor visibility into daily store sales, POS may be the right starting point.
A CRM tracks leads, customers, interactions, opportunities, follow-ups and sales pipeline. It is useful when the problem is remembering who to contact, understanding sales activity or managing long relationship cycles rather than retail checkout.
A small business can use both POS and CRM because the same customer can have a transaction history and a relationship history.
ERP systems typically connect finance, purchasing, inventory, sales, operations, HR or other functions around shared records and controls. They are valuable when departmental tools create duplication or management cannot see the whole operation.
ERP should not be the default answer simply because a business is growing. The cost and change burden must match the operational complexity.
Write down the decisions you cannot make today, the duplicate work people perform, the records that conflict and the approvals that disappear in chat or paper. Those symptoms point to the system boundary you actually need.