Diference between at the corner and in the corner

In the corner of is used when referring to a concept of closed space.
At the corner of and on the corner of are used to indicate an open space, say street or park.

Examples:
The tree is at the corner of the street.
The tree is in the corner of the street.

Diference: In time, On time

"On time" means exactly at the appointed time, either before or after:
Sentences:

 The match begins at 4:30. I will be there on time. El partido empieza a las 4.30. Yo estaré allí puntual (llegaré a las 4.30, ni antes, ni después)

 The bus leaves at 3. I will be there on time.  El autobús sale a las 3.00. Yo estaré allí puntual (justo a las 3.00)
 "In time" means with a lot of time before anithing begins.
Sentences:

 The match begins at 4:30. I will be there in time. El partido empieza a las 4.30. Yo estaré allí con tiempo (llegaré antes de las 4.30)

  The bus leaves at 3. I will be there in time. El autobús sale a las 3.00. Yo estaré allí con tiempo (antes de las 3.00)

Bibliography:
http://www.wikilearning.com/curso_gratis/curso_de_ingles-by_the_time_on_time_in_time/3405-38