The 5' position of a nucleoside bears an OH group, whereas the 5' position of a nucleotide bears a phosphate ester. Because the examples are from RNA, they bear 2' OH groups. These experiments were performed by Erwin Chargaff, and lead to what became called Chargaff's Rules. These results were critical for the Watson and Crick double helix DNA model. Thus a G-C base pair shares three hydrogen bonds.
More hydrogen bonds means more robust pairing, and thus more robust information storage.
DNA and RNA are both nucleotide polymers and both carry information within a cell. DNA is made of 2'-deoxynucleotides whereas the ribose of RNA bears a 2' OH group. As found in the cell nucleus, DNA has two strands and RNA has one strand. Franklin's DNA x-ray diffraction data revealed that the DNA molecule was a helix, 20A in diameter, and had a density that was inconsistent with a single helix. From this Watson and Crick correctly concluded that DNA was in fact a double helix.