What is difference between line current and phase current?

A 'phase current' is the name given to the current in a phase and a 'line current' is the name given to the current in a line.

'Lines' are the conductors that connect a three-phase load to a three-phase supply.

'Phases' are the individual windings in a machine, or the individual impedances that make up a three-phase load.

In the case of a star (wye) connected load, the line current is numerically equal to the phase current.

In a the case of a balanced delta connected load, the line current is 1.732 greater than the phase current.