So I think from reading about them, the niche for the longbow was to shoot as ‘clout shooting’, or shooting into an area as opposed to specific individual targets, to a distance of 250 meters or maybe more, with relatively heavy killing arrows.
Whereas the recurves had a bit more range with flight arrows but were used at that range to wound and harass. Both weapons had a relatively short range for shooting individual targets closer to around 50 meters. For the Steppe Nomads, that is where the killing was done. They could take advantage of their mobility to cause incremental damage at what was for them a safe range, then move in closer for the kill when the enemy morale was wavering.
Crossbows, especially when used supported on a wall (or on a pavise, the gunwhale of a boat, the side of a wagon etc.) could hit individual targets out to about 150 meters. The Mongol secret history describes their horses being killed at (what we think is) about that range. They were also used for ‘clout shooting’ depending on the circumstances, but were apparently not as effective in that role.
Crossbow bolts were as we have already noted, much shorter as well as being heavier. They also had paper instead of feather vanes and usually only two instead of three as was more typical on bows (? or was it?)
Crossbows were also used on horseback, as were (somewhat surprisingly) longbows apparently though so far as I could determine, not until the 16th Century and mostly up in the Scottish border region.