Transcriptional and translational reporter gene fusions are two methods of using a reporter gene to assay transcriptional activity.
A transcriptional fusion gives two protein products: one of the gene of interest, and the other of the reporter. This doesn’t allow the localisation of the protein product of the GOI, but does allow assaying of the expression level in vivo.
A translational fusion allows the production of a single protein product, with the GOI and reporter combined to a single protein. This is done by placing the reporter under the ribosome binding site for the gene of interest. This allows the localisation of the protein of interest, with the use of fluorescent proteins, allowing tracking through the cell by optical microscopy.