The phrase "All X are not made equal" (where 'made' can be substituted for any method of creation) derives from the phrase "All men are not created equal", a phrase used to contrast the popular adage "All men are created equal", most famously used in the US Declaration of Independence, penned by Thomas Jefferson:
We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty, and the Pursuit of Happiness. That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed;
The sentiment it carries is that some type of a given thing are inherently better than another, due to some aspect of how they were created (born of a 'better race' or from a 'better manufacturer'), e.g. "Not all mean are created equal" for eugenics, "Not all cars are created equal" might be used to suggest one brand is inherently better than another, etc.
Being that it is part of the US Declaration of Independence, US citizens are far more likely to recognise that phrase than others, though it is a fairly well known phrase.
‘At all’ means ‘in every way, in any way’ and has been so used for around 600 years. It is now mostly found in negative and interrogative sentences. The ‘all’ element is perhaps self-explanatory. ‘At’ has many uses, not necessarily confined to the location of objects in space and time. They include the now obsolete ‘introducing the reason or consideration’ (OED), which is one possible source for its use in what must now be regarded as an idiom.
Best Answer
That's it is an expression that means:
Or
That's all doesn't seem to be an expression all by itself, but means that there's nothing more to it, that's all you have to do, etc.
So in some cases, as in the second example from the Cambridge Dictionary, they could be used the same way with a slight difference in meaning.