DNA & RNA codon charts

Why does the Adenine nucleotide in the codon for leucine, as an example, not change between the DNA codon chart, and the RNA codon chart?

Shouldn’t, for example, the codon TTA become AAU? when transcribed from DNA to RNA

hello! I actually don’t know the main cause but the reason might be that in some nucleotides only the first two are enough to code for something, so when the third one is changed the protein is still coded. that might be the reason why but I don’t know the background of it