The t-slot profile has a T  shape groove on each side, while the v-slot has a beveled edge. Even this minor difference results in varied applications of both profiles. V-slot profiles have beveled edges to ensure that wheels and bearings sit inside the shape.
The v-slot directive is used to direct content to a named slot. The shorthand for v-slot: is # . The v-slot directive can also be used to receive data from scoped slots, provided by using v-bind in the child component.