During the past few decades, gravity cantilever retaining walls (GRW) have shown a relatively reliable performance. However, mechanically stabilised earth (MSE) retention systems have grown in popularity as they are cost-effective and have demonstrated resilience through recent seismic events. In this study, utilising 2D finite element (FE) modelling with OpenSees and the Manzari and Dafalias constitutive models, we have compared the seismic behaviour of GRW and MSE systems, both designed for the same conditions, under three earthquake records. These earthquake excitations were recorded on engineering bedrock (Vs > 700 m/s) to avoid complexities of deconvolution. Our investigations indicate that the retained MSE reinforced soil block behaves similarly to a rigid block, while this is not the case for the soil over the foundation heel in the GRW system. In addition, the lateral displacement over the height of the wall for MSE is at about half that of a GRW. In the final section of this paper, we discuss the effect of backfill compaction. It is shown that regardless of the retention system, the backfill density increasing from medium (Dr = 70%) to dense (Dr = 100%) reduces the lateral displacements by at least 50%.