What is the function of a fixture and a jig? Please also explain the difference of them

Connecting rod bearings are to be replaced. The journal measures 70.866 mm (2.790 in.)​. The standard rod journal diameter is 71.12 mm (2.800 in.). What size bearings should you order from the parts room?

1- Draw three views of hexagonal nut for 24 mm diameter bolt according to rough rule dimension. 2- Two plates to be fastened by means of bolt thickness of plate 50mm use a bolt of dimension M14X2-RH, provide with a suitable washer, draw the top view, front sectional view, and side sectional view. 3- Use hexagonal bolt, nut and washer by suitable dimension to join the tube holder in figure below.

List 2 one non-Grashof (triple rocker) mechanisms that are used in industry. Justify why each mechanism belongs in the "one non-Grashof" group. (Please provide picture of mechanism)