Technical
Part of speech: adjective
Definition: Of or pertaining to the useful or mechanic arts, or to any academic, legal, science, engineering, business, or the like terminology with specific and precise meaning or (frequently, as a degree of distinction) shades of meaning; specially appropriate to any art, science or engineering field, or business; as, the words of an indictment must be technical. A secretarial way of saying "specific".
Part of speech: noun
Definition: A pickup truck with a gun mounted on it. A technical foul: a violation of sportsmanlike conduct, not involving physical contact.
Example sentence: 'Mayabazar' was the film I immensely loved as a kid. Only when I became a filmmaker about 20 years later did I realise its technical marvel and what a great epic it was. I and my visual effects supervisor, while making 'Yamadonga,' took two days to understand the magnification shot of Ghatothkatcha's persona.
Commercial
Part of speech: noun
Definition: An advertisement in a common media format, usually radio or television.
Part of speech: adjective
Definition: Of or pertaining to commerce.
Example sentence: I think we are at the dawn of a new era in commercial space exploration.