Quick answer
Concealed wiring runs cables through conduits buried inside walls and ceilings, so nothing is visible — the neat, standard choice for modern homes. Surface (conduit) wiring runs the cable through conduit or casing mounted on the wall surface, which is quicker and easier to inspect or modify but more visible.
Concealed wiring looks clean and protects cables well, but faults are harder to reach, so quality matters more — using durable, rodent-resistant and fire-safe wire is wise because you won't be replacing it easily. Surface wiring is common in workshops, extensions and temporary setups.
Either way, use correctly-sized, good-quality house wire and have the work done by a licensed electrician. See how to choose the right cable.