Updated: Nov 27, 2020
The view: sliding doors are going to offer the most unhindered view of the outside. Go for two large panels, one sliding over the other, to give two wide apertures. However, bi-fold doors only offer a full view when completely open.
Access: If it is about access bi-fold doors can be more versatile. They open the whole space, or you can open one panel for everyday use. They are also better for creating a level threshold between outdoor and in so better suited to wheelchair users, and there is no lip for people to trip over.
Thermal performance: it is not always the case, but more frames in bi-fold doors means more chances of thermal bridging which can lead to some sliding doors being better at keeping heat in.