Expressions used with encoders

 

While I am reading and collecting information about rotary encoders , I faced some troubles about the meaning of some expressions concerned with encoder ,which make me to be confused and stray,  these expressions or words are :

-Count per revolution (rotation) 

-Pulse per revolution

-Tick per revolution

-Transitions per revolutions 

-Number of transitions

-Number of state changes


I thought the transition is same as state changes which means change from high to low or low to high , but what about the others what is the diffenece among them (count , tick ,pulse ,transition .... etc)? and what the relationship between transitions and pulse ? Could anyone clarify that , please