the difference between aim and objective

Aims and objectives are always linked, but often confused.  They are, however, quite distinct:

Aims are the changes you hope to achieve as a result of your work

Objectives are the activities you undertake and the services you offer to bring these changes about

Defining your desired outcomes is part of good project planning.  Outcomes are linked to your aims, so defining clear aims will help you identify your outcomes.

(source: http://www.ces-vol.org.uk/index.cfm?pg=123)

Their planning triangle at

http://www.ces-vol.org.uk/index.cfm?pg=124