What is the difference between a joint and a fault?

Joints and faults are types of fractures. A joint is a fracture along which no movement has taken place, usually caused by tensional forces. A fault is a fracture or break in the rock along which movement has taken place. One might expect more earthquakes to occur near faults.

Explanation:

Fractures include joints and flaws. A joint is a fracture along which there has been no movement, which is generally generated by tensional pressures. A fault is a fracture or break in the rock that has allowed movement to occur. Near faults, more earthquakes are likely to occur.

the statements that apply here about binary star system are

"have stars that might appear to wobble"

"often have one star that is brighter than other"

a binary star is a star system consisting of two stars revolving around their common barycenter. systems of two or more stars are called multiple star systems.