How can organisms be so unique if the nucleotides making up dna are all the same between organisms?

All organisms are made up of the four nucleotide bases of the DNA. Yet still all organisms are different from one another due to the sequence of the arrangement of these nucleotides. The pattern of arrangement of the nucleotides determines which organisms will be more similar and which will be more different from one another. The pattern of arrangement leads to the formation of genetic code which will differ in organisms. Hence, all organisms are made of the 4 nucleotides but differ due to the pattern of arrangement of the nucleotides.

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.