Lua Difference between Instant and Conjure?

[LoL-Up]

Someone LUA programmer could help me understand the difference conjure spells and instant?

for example I have 2 OT servers here

The Create Food A server:

Spoiler: Server A

<instant name="Food" words="exevo pan" mana="30" soul="1" aggressive="0" selftarget="1" exhaustion="2000" needlearn="0" event="script" value="support/conjure food.lua">

The Create Food B Server:

Spoiler: Server B

<conjure name="Food" words="exevo pan" needlearn="0" maglv="0" soul="0" mana="30" selftarget="1" aggressive="0" script="support/conjure food.lua">