Short answer: In VPS plans, 'bandwidth' usually means the monthly data-transfer allowance (for example 2 TB), while port speed is the maximum throughput at any moment (for example 1 Gbps). Unmetered plans remove the monthly cap but keep the port speed and a fair-use policy.
Bandwidth vs port speed explained
Strictly, bandwidth is a rate (bits per second), but hosting plans use the word for monthly transfer volume. A plan with 2 TB of transfer on a 1 Gbps port can move up to 2 terabytes a month, at up to one gigabit per second.
When you exceed a metered allowance, providers charge overage per terabyte or throttle the port. Unmetered (or 'unlimited') plans do not count bytes, so the practical ceiling is port speed times the hours in a month: a fully used 100 Mbps port moves about 32 TB a month, a 1 Gbps port about 320 TB.
VPNs, proxies, media servers and backups are traffic-heavy and benefit from unmetered plans; websites rarely use more than a few hundred gigabytes.
See it in the data
Frequently asked questions
How much bandwidth does a VPS need?
A typical website uses well under 1 TB per month; VPN, proxy and media servers can need several terabytes or an unmetered plan.