A Brand Ambassador would be one who is not only a spokesperson for the brand or is just appearing as a testimonial for the brand’s benefits. He/she is an integral part of the brand persona and helps to build an emotional, which goes beyond just appearing on TV commercials. For example, Fardeen Khan is the brand ambassador for Provogue while he remains a brand face for Lux Body Wash.
On the other hand, a Brand Face would be the current celebrity who is just used as a tool to increase brand recall and is only appearing in the advertisement. It is usually seen that a brand face is a temporary contract and is very short term at times. An example would be Sona Chandi Chawanpryash using Sourav Ganguly for a while in its commercials. Brand faces are easily forgotten and fade away with the campaign’s end.