Well different codes denote to different chemical engineering degrees. H800 is for the BEng, H801 is for MEng. Other codes like H813, H810 denotes to Chemical Engineering with another subject such as energy, business etc... So the codes do matter in that sense. If the job description asks for a MEng, then you choose the code for it. But usually, you're able to switch mid-degree so don't work yourself up too much.