How OceanGate's Titan Submarine Works

This is not a submarine, but the Titan, is a, Cyclops-class manned submersible.

But,what's the difference between the two ?

The primary difference between a submersible, and a submarine, is that the submersible is launched from a mother vessel or home vessel.

They are typically launched on a raft or platform, which is placed into the ocean! and ultimately descends via four electric thrusters, which helps it to reach speeds of around 3 knots.

But a Submarine can dive underwater, without any external equipment, and surface all through the process of buoyancy.