pact of blade vs bind pact weapon

[TheFibrewire]

does both use Spell casting modifier?
I am using Wyll as debuffer with melee and wearing medium armor and want to give him a glaive for reach. Let us say I gave Wyll the glaive Sorrow, and decided to use Pact blade spell on it

I want to understand the difference between them. also will binding a weapon use Charisma modifier as the summoned weapon uses charisma modifier.

[Goten]

Its always better to bind an existing weapon as it gets bonuses to damage and attack roll and the CHA modifier than using a plain summoned pact weapon.

[Morgian]

Yes, both types use CHA as attack and damage bonus, but must be renewed every long rest (at least when summoned).
I ignored bound weapons until I got Sarevoks sword, which I used till the end.

[ComradePreacher]

Binding existing weapon is better if it's a +1 weapon or has abilities.

Summoning a pact weapon is essentially a mundane weapon probably good early game if you have nothing better. Most of the summon weapons are polearms and heavier two handers.