What is the difference among firing accuracy and weapon accuracy?

Item with firing accuracy : SUE
Weapon accuracy : skill multishot, perk
I don’t get the point of firing accuracy and weapon accuracy.
what is the exact meaning of them? I searched this forum, but found nothing.
Is it the maximum increased crosshair? or Is it increased time for crosshair to be the maximum?
Is it worth to put the perk point? if so, what kind of weapon is good for this perk?
If we put more skill point to Multishot skill, Maximum crosshair size is decreased.
and it is said weapon accuracy is increased in this case. and then, if we put the perk point to increase
firing accuracy, multishot skill also got benefit too?
If someone knows well, plz share your own knowledge.

and xpertise weapon accuracy , we should invest 10 points in it?

i got damage and crit 4/4 (20 points)
armor/elemental defense/ weapon accuracy/ afliction 3/3/3/3 (24 points)
power regen 1

last 5 points where should go? 1 for sprint? and last 4 i am not sure if add them on afliction cuz i dont use elemental dye (i prefer shadow for increse crit chance ) or in weapon accuracy ( i am not sure whta this expertise does exactly)

if some1 can clear what exactly firing acuracy /weapon accuracy does will be good