Whats The Difference Between The ATMEGA328-PU and the ATMEGA328P-PU ????

hello & Good-Day to you all !!

I am looking to buy 5 microcontrollers but want the ATMEGA328 but there are two types and i can find any difference in the data sheets about them, please could anyone help me find out the difference ?

There is Either the:

ATMEGA328 PU OR:

ATMEGA328P-PU

and i am really struggling to find the list of differences as i did find a webpage that details all the differences (i think there was 4 or 5 differences but cant remember it was so long ago & didnt bookmark the page! )

Please could any of you legendary Arduino Guru's help me with this ???

Many many thanks in advance for any help given !

Signature Bytes are different

ATmega328 0x1E 0x95 0x14
ATmega328P 0x1E 0x95 0x0F

328P has some subtle feature differences that most users will not notice.

You can copy a portion of avrdude.conf & make a new part for the 328's, and do the same in boards.txt.