Ambiance is from French ambiance "atmosphere, mood, character, quality, tone," from Latin ambiens "a going around," present participle of ambire "to go around," from amb- "around" (from PIE root *ambhi- "around" + ire "go".  According to the Oxford English Dictionary, the first known use of "ambiance" in English was in 1648, appearing in a "Letter from a Nobleman". 

What is the difference between ambience and ambiance?  While 'ambiance' is more commonly used in American English, 'ambience' is preferred in British English. However, both convey the same meaning - the character or atmosphere of a place.  Ambience comes from the Latin "ambire" meaning "to go around."  The earliest known use of the word ambient is in the late 1500s. OED's earliest evidence for ambient is from 1572, in the writing of John Jones, physician.

Examples of ambiance in a sentence: 

• "At once, the atmosphere and ambiance around her changed."
• "The track has the flat ambiance and limited dynamic range common to these films."
• "However, the ambiance and background noises are in full effect with great dynamic range."
• "Just like everywhere else on the island, the spa had an ambiance of relaxed elegance." 

Italian "ristorante, plural ristoranti", or restaurants, in America almost always have Dean Martin, "The King of Cool", adding to the ambiance.  Dean Martin was born Dino Paul Crocetti,  

2 hours ago, Bill W said:

Ambiance is from French ambiance "atmosphere, mood, character, quality, tone," from Latin ambiens "a going around," present participle of ambire "to go around," from amb- "around" (from PIE root *ambhi- "around" + ire "go".  According to the Oxford English Dictionary, the first known use of "ambiance" in English was around 1923. 

What is the difference between ambience and ambiance?  While 'ambiance' is more commonly used in American English, 'ambience' is preferred in British English. However, both convey the same meaning - the character or atmosphere of a place.  Ambience comes from the Latin "ambire" meaning "to go around."  The earliest known use of the word ambient is in the late 1500s. OED's earliest evidence for ambient is from 1572, in the writing of John Jones, physician.

Examples of ambiance in a sentence: 

• "At once, the atmosphere and ambiance around her changed."
• "The track has the flat ambiance and limited dynamic range common to these films."
• "However, the ambiance and background noises are in full effect with great dynamic range."
• "Just like everywhere else on the island, the spa had an ambiance of relaxed elegance." 

As I understand this, ambience was in English usage and spelling since around 1572 and ambiance became an alternate spelling for the same word around 350 years later in around 1923. My Macquarie dictionary only gives the spelling ambience as Australian usage. It also points out that ambi means "around" or "both" as in ambidextrous.

It is interesting to note that Merriam-Webster uses the Oxford and Macquarie spelling ambient for the related adjective rather than what you might expect, ambiant.

Just the facts:

Ambience Definition & Meaning - Merriam-Webster