They are still talking about the same genes. The LHON genes are known to be the blueprint for part of a chemical called NADH Dehydrogenase or ND for short. This is a big chemical made up from smaller building blocks called sub-units. The 3460 gene is also known as ND1 and the 14484 is also known as the ND6 gene. All genes are codes tellling the body how to make important chemicals called proteins.
Every protein is made up of smaller chemicals called amino acids.
Each protein is like a string of beads, where each bead is an amino acid. Each tiny part of a gene represents the amino acid to use for that 'bead'. In the case of the mitochondrial DNA, the 11778 gene normally tells the body to use the amino acid called arginine in a particular position in the chemical ND4. If the 11778 gene is the LHON mutation, then it does not represent arginine, but instead tells the body to use a different amino acid called histidine . This difference makes the protein less good at doing its job.