What is coherence and what is interferernce explain diffrent type of interference with neatly

Two wave will be coherent when they have the wavelength, amplitude, and phase of the constituent wave forms must be identical.

Where as interference is the  addition of two  wave considering the mathematical sense while adding them.

when two wave of same sense add together they for constructive interference. like two +ve sense or -ve sense will form constructive interference.

when the are are of different sense the form destructive interference.   like one positive wave added with -ve one.

waves moving from a fast medium to a slow medium will experience a reflection as light travels more slowly than red light. total internal reflection occurs when the critical angle is.