A payment gateway and a merchant facility solve different parts of accepting a payment, even when one provider packages both together.
The gateway
The gateway is the technical connection between a checkout or business system and the payment-processing chain. It can capture payment details, tokenise cards, apply fraud rules and send transaction instructions securely. A gateway does not necessarily provide the underlying merchant acquiring relationship.
The merchant facility
The merchant facility is the commercial arrangement that enables a business to accept card payments and receive settlement. It is commonly provided by a bank, acquirer or payment service provider. The arrangement covers pricing, settlement, chargebacks, risk obligations and supported card types.
Bundled versus separate
A bundled solution is easier to establish and reconcile. A separate gateway and acquirer can offer more flexibility, redundancy or negotiating leverage, but introduces integration and support complexity.
When comparing options, map ownership of checkout, token storage, fraud controls, processing, settlement and customer support. Ask whether saved payment tokens can be transferred if you change provider. Also check settlement timing, reporting quality, refund workflows, recurring-payment support and total fees.
The best architecture is not automatically the one with the most components. It is the one your business can operate reliably while preserving appropriate control and portability.