INTRODUCTION:
The referential theory: this idea states that a term gains its meaning by standing for a word, And meaning of the proposition is correspondence of its parts with elements of the world. The mediated reference theory: This idea puts forth The aspect that words are expressing the external world, but they are having just more than the referent’s information. The mediated reference theory is different from the direct reference theory. Truth conditional view: This view is to the following idea that the meaning of the proposition lies under the conditions under which it is true. Sense is considered to be the “mode of presentation of object” ; it could be colloquially understood as the name denoting object. Whereas the “reference” on the other hand could be interpreted as the delicate connection between sense determining the reference and different terms with different senses refreshing to the same object. 
MAIN IDEA:
Sense is in the direction of reference and it is determining the contours of reference. The reference on the other side, is in correspondence with the truth value of the statement. Sense and reference are different but they are still interconnected in the manner that sense is the manner of presenting an object existing concurrently with determining its reference. Let us take for example, “The present king of France” and if we are saying that “the present king of France is bald” he believes that all of these statements are true, it is simply by the virtue of the fact that the statements are falling under the category of null class and null class includes all classes as per Frege.
What Frege wants to assert is that: Each sign is corresponding to a sense. Each sense corresponds to a reference. A reference has multiple correspondence with signs and a single sense could be showcased through different expressions of different languages. “On sense and reference identity gives rise to challenging questions which are not altogether easy to answer.” Even though “the morning star” and “the evening star” have the same reference — the planet Venus — the sentences seem quite different, as has been asserted by the University of Notre Dame, Jeff Speaks, who further expands the horizon of this idea by highlighting that:
“Frege believed that these statements all have the form ‘A = B’, where ‘a’ and ‘b’ are either names or descriptions that denote individuals. He naturally assumed that a sentence of the form ‘a = b’ is true if and only if the object a just is (identical to) the object b. For example, the sentence ‘117+136 = 253’ is true if and only if the number 117 + 136 just is the number 253. And the statement ‘Mark Twain is Samuel Clemens’ is true if and only if the person Mark Twain just is the person Samuel Clemens.”
It is a well evident claim that has been leveled by this philosopher that the semantics and syntax are interrelated in a particular given proposition, and the logical syntax is task with the work of investigating about the as well as examining the logical status of the language, whereas on the other hand The semantics, which are broadly of two categories or aspects: Is falling as sense and reference. The work with semantics is essentially tasked with is, Examining about and interpreting the language with its connection to the external world.
CONCLUSION:
The essential respect which this philosopher attempts to highlight in his article in sense and reference is the very fact that he disagrees with the idea that identity is a relationship between the names or the sign of the object. He stands in opposition of this argument. With this, the concept of equality, which is generally presumed in the connection to the propositions as a matter of relation between things or objects, By this logic, the morning star is the evening star and the evening star is the evening star. These two propositions are equally same, and they are not providing any substantial increase in the potential of our knowledge.
But we know this thing for sure that there is one particular proposition that when we say that the morning star is the evening star is increasing the actual potential of our knowledge by adding to the information by providing the fact that the term which is named as the morning star is equivalent or rather similar to the entity, which is named as the evening star- It has increased the quotient of our information processing by adding this new proposition with the relevant new information. That is the primary reason why Frege Is standing in the affirmative of the motion that Equal is a special relation where a thing can only stands in relation to itself and not to other things.
REFERENCE:
https://www3.nd.edu/~jspeaks/courses/2011-12/83104/handouts/frege-sense.pdf
https://plato.stanford.edu/entries/frege/
Russell, B., “On Denoting”, Mind Journal: Oxford, 1905, pages: 479-493.
