Difference between Megafunction and IP Cores

Hi,

Still confuse, to my understanding. Megacore is the individual component in the Megafunction which can access from Megawizard plug-in manager.

Accroding to my finding:

megacore functions

Altera® MegaCore functions are developed and pre-tested by Altera and are optimized for specific Altera device architectures, allowing user-specified performance utilization goals to be met.

megafunctions are ready-made, parameterized, pre-tested blocks of intellectual property that are optimized to make efficient use of the architecture of the targeted programmable device. By using megafunctions, designers can focus more time and energy on improving and differentiating their system-level product, rather than redesigning common functions.

I also see IP core megafunction often used interchangeably.

So does that means Megacore = Megafunction = IP cores?

Can sme expert enlighten me?