Key Difference: Surname is the family name that that one shares with other family members. This name is passed from one generation to the other. On the other hand, title is additional term that is also used to address a person and is generally added either before a name or after the name. This term can be used in numerous contexts. A surname is acquired through the previous generations, whereas a title may or may not be acquired due to previous generations. It may be used to show the respect or to acknowledge the achievements of an individual. 

It is easy to define surnames as they are used in same context. They define the family name that has passed from one generation to the other and thus it is shared by family members. The surnames were developed in the Middle Ages in order to identify a person with same forename as the other.

The surnames were based on various attributes like location, occupation, appearance, etc. In order to maintain this distinction criteria, it got transferred in next generations and even today, the same pattern is being followed. On the other hand, defining a title is difficult, as it is used in many contexts. A title is also used to address a person. It provides the additional information depending upon the type of title.

Let us find out some of the important titles and their usage.

1. You must have addressed somebody like Mr. Arthur or Ms. Lily. Mr. and Ms, here denotes the adult male and adult females respectively. These titles are used as prefix to the names and are widely used in English speaking areas. Similarly Mrs. as title is used to denote a married woman; Miss is used to denote a girl child or an unmarried woman. Similarly there are other titles which are used to formally address a person.
2. Honorific occupational titles: these are used in context to the profession. For example a person who has completed his Ph.D. may be referred as Doctor. Other such titles are officer, coach, etc.
3. Aristocratic titles: In modern times, these titles are used to in context to sons and daughters of ruling monarchs or related to the royal dynasty.  It includes titles like- Prince, Duke, Count, etc. 
4. Military titles: these are used to define the ranks of the personnel. For example – Colonel, Captain, etc.
5. Honorary titles: these titles represent the honour towards the person. Mahatma is an example of honorary title that was given to Mahatma Gandhi of India to recognize his contributions in the nation’s freedom.

Some of the titles used in British Isles nobility are Duke, Earl, Viscount etc. Apart from these, there are several other titles. Titles are additional to personal name of the person, whereas surname is a part of personal name. Another difference between them is that a surname is shared by the family members, whereas the titles are not restricted by this condition.

A surname may define an ancestral line, whereas titles generally do not speak about the ancestors. However, aristocratic titles may be an exception in this regard. Surname usually appears at the last of name and is therefore also named as last name (except in countries like China, Japan, etc) whereas titles (in context to Mr. or Miss) usually appear before the name.

 Surnames are based on one’s history, and that history is related to the ancestors, whereas the titles are based on various current attributes of an individual like position, academic achievements, outstanding achievements, marital status, etc. Referring a person with his surname is mostly defined as a formal reference, whereas titles are generally associated with respect and proud. Therefore, we can say that both these terms are different to each other in many contexts.

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