I have assumed this is not a Class or Homework Question, as they are not allowed under the CR4 Forum Rules.
Bearing Standards are Standards used by most major Bearing Makers.
The Standard Bearing Numbers are used by Makers, who have agreed to make bearings to certain specifications, using a "common between those manufacturers" reference number for each different type/specification of bearing.
Before bearings can be selected, many different variables must be known:
Load carrying
Radial or Axial
Sleeve, roller, tapered roller, spherical roller, ball, lignum vitae, graphite, ceramic, cast iron, babbit metal.....a very long list.....
"Almost" Good Answers: