Bandwidth / link rate
Bandwidth is capacity. Consumer internet plans often advertise rates in megabits per second (Mbps) or gigabits per second (Gbps). That is not the same as how many megabytes a file transfers each second.
Throughput
Throughput is the useful data rate actually achieved. Protocol overhead, server capacity, congestion, Wi‑Fi conditions and device performance can make it lower than a nominal link or plan rate.
Latency
Latency is delay, often expressed in milliseconds. Interactive applications such as calls and online games can care more about consistent low latency than about extremely high bulk-download bandwidth.
Jitter
Jitter describes variation in packet delay. Real-time audio and video can be affected even when average bandwidth is sufficient.
Packet loss
Loss causes retransmissions for protocols such as TCP and can degrade real-time traffic. Persistent loss is a quality problem, not something a faster nominal plan automatically solves.