Answer-

Diffrence between Tetragonal and trigonal system

Tetragonal Crystal System - Tetragonal System is one of the structural categories to which crystalline solid can assigned. Crystals in this system are reffered to three mutualy perpendicular axes, two of which are equal in length.

Trigonal Crystal System - The Trigonal Crystal System is defined by three fold rotation axis. Is a limiting case of the simple monoclinic bravais lattice.