They are not different. They are exactly the same, What you are mixing is external representation of expressions vs. the internal one.
Here is the TreeForm of
And here is the TreeForm of
You can see the internal representation is the same.
But the external representation of the first one and the second one are
To control the external representation it means you have to fight the frontend and have to use things like Hold
or HoldForm
or Inactive
and so on to prevent evaluation. But this buys you nothing, Since to be able to use the expression you have to release the hold. So you end up with just more complicated code to look at.
If you are interested in final expression representation only, and not during computation, then you could always do that at the very end using the Hold
functions mentioned above. If this is what you want, it will be easy to do that.
expr = {a, a + b, a + b + c, a + b + c + d, a + b + c + d + e}/2
"gamma" type
Expand[expr]
Alpha type
DisplayForm[FractionBox[Numerator[#], Denominator[#]]] & /@ expr
I would actually do everything using MateX, since it is just for display purposes. Here is an example
Alpha
<< MaTeX`
expr = {a, a + b, a + b + c, a + b + c + d, a + b + c + d + e}/2;
s = "\\frac{" <> ToString@TeXForm[Numerator[#]] <> "}{" <>
ToString@TeXForm[Denominator[#]] <> "}" & /@ expr;
MaTeX[s]
Beta
s = "\\frac{1}{" <> toX[Denominator[#]] <> "}\\left(" <>
toX[Numerator[#]] <> "\\right)" & /@ expr
MaTeX[s, Magnification -> 1.3]
Delta type could be done similarly.