The Ray-Ban RX5294 and RX5154 frames differ primarily in their design and shape. The RX5294 features a more modern, rectangular silhouette, which appeals to contemporary aesthetics, while the RX5154 has a classic, rounded shape that evokes a vintage look. Additionally, the materials and color options may vary between the two models, catering to different style preferences. Ultimately, the choice between them often comes down to personal style and face shape compatibility.