What's the difference between availability, reliability and maintainability for equipment?

In any process industry or system, its performance as a whole is dependent on the smooth function of each section or equipment. Now a RAM (Reliability, Availability and Maintainability) analysis is done to get a quantitative depiction. Here,

Availability is the time an equipment remains operational to perform its required function, in a specific time period.

Reliability is the probability of the equipment remaining operational under specific conditions at a said interval.

Maintainability is the measure of ability of the equipment to be brought back to the accepted condition of its operation, with prescribed practices and techniques.

All the above factors contribute to the effectiveness of an equipment.

Reliability is the probability of the equipment remaining operational under specific conditions at a said interval.

Maintainability is the measure of ability of a maintained  equipment to be brought back to the accepted condition of its operation.

Availability is that time for equipment remains operational to perform its required function and it depends on Reliability and Maintainability

In relation to maintenance of equipment, availability is the useful work maintained successfully. Meanwhile reliability could be the achievement during committable operations in a system 

Reliability: amount of time equipment operates in one year. (operating hours per year/ 8700hours)

Availability : operating hours per year / (8700-planned downtime hrs)

maintainability : to return the assest as its original condition