I got this question in one of my groups.This kind of a question takes some time to answer. Hence, I am writing this article. You can, of course, apply the principles to similar questions using different Ascendants.
First of all, the Ascendant is comprised of both appearance and mannerisms. This includes mode of dress, body movement(graceful or not graceful, for example), manner of verbal expression(friendly or not friendly, for example), facial features and emotional expression(stoic or cries easily, for example). So,as a first step, one must understand the basic nature of each of the signs. It is fortunate that adjacent signs are very different.
In this case, Gemini is very different from Cancer. I am a good person to answer this question because I am a Gemini Sun, Venus and Mercury and a Cancer Moon. This makes me very different in different spheres. Gemini is very extroverted, friendly, and chatty. Gemini likes to do many things at one time, such as talking on the phone and giving the pet a bath, while stirring the soup.Geminis are very curious.They are excellent conversationalists because they truly want to know what makes people tick.
Geminis are not, usually, shocked by weird things. Our minds are very flexible and we are open to many avenues of exploration. When you talk to a Gemini, they can talk about most subjects with some understanding because they know a little bit about a lot. They are, usually, voracious readers. Physically, Geminis look impish and intelligent. They have a look of mischief about them. Charlie Sheen is a Gemini Ascendant and embodies this Gemini look.
Cancer is very, very, very different. Physically, they have a sweet, gentle and dreamy appearance. They, likely, have beautiful eyes. Their eyes are said to be as deep as the oceans. Cancer is not a gregarious Ascendant. They would not be the life of the party. The Gemini Ascendant may be. If not the life of the party, then the life of the “intellectual” party.Where there are interesting discussions, Queen Gemini is holding court.
The Cancer Ascendant is likely a warm, deep feeling person. They would have a kind of “homey” vibe about them, as if one could invite them over for a lunch of home made bread and soup and one could share family photos. They seem to love pets. Their homes are their castles. Their homes, likely, smell good and have many homey touches such as candles, family photos and many kitchen utensils and devices. They, likely, love to cook .Medically speaking, Cancer signs may have stomach issues. They displace their emotions into their stomachs. They are very loyal and tend to have a small group of close friends.
I hope this has helped to make the distinction between these two Ascendants.