Macmillan Dictionary defines “topic” as “a subject you write or speak about”, while a “subject” is “an idea, problem, or a situation, etc. that you discuss or write about.” Sounds confusing? Though loosely interchanged, the two words actually have a slight difference and can be distinguished from the other.
The difference between Topic and Subject
Longman Dictionary gives us a better perspective of the difference. “Subject” has different meanings in different contexts. In the context of school, “subject” refers to “an area of knowledge that you study at a school or university.” Collins Dictionary explains “topic” as “a particular subject that you discuss or write about.” From these definitions, we are able to understand that “subject” has a broader or wider meaning while “topic” is an aspect or subset of a “subject.”
Example of when to use them
For example, your teacher asks you to write about science (subject). Students may write about earth science (topic), chemistry (topic), physics (topic), or biology (topic). Or perhaps, your client wants to know more about insurance (subject). You can consult and ask if he is referring to personal (topic) or corporate (topic). If for personal use, ask if he is interested in home insurance (topic), health insurance (topic), car insurance (topic), or general insurance (topic). If for business purposes, he might need professional liability insurance (topic), property insurance (topic), or business interruption insurance (topic).
Meaning of Topic and Subject in a nutshell
So in a nutshell, a “topic” is more specific than a “subject.” The latter has a broader perspective versus the former, which can be more specific and particular.