Here are some of your answers.

1)What is difference between hide & suppress ?
"Hide" removes the object from the display. It is still calculated in mass properties and is still an active part of the model. "Suppress" temporarily removes the feature from the model. It's effect is similar to "Delete", but it can be reversed by using "Resume".

2)What is difference between mate & align?
"Mate" is like putting your hands together palm to palm. "Align" is like putting your hands together with both palms facing up.


4)What is packaging in assembly?
"Packaging" allows you to place a model in an assembly without constraining the model.