Yes basically the number/letter designation is the same. There are variations of the 420a such as the Neon VS Eclipse/Avenger. The platform is the same.
#4507, "RE: A588 - 420A" In response to Reply # 4 Dec-17-06 09:56 AM by Star Turbo Talon
Originally posted by mcgyvr a558 is the designation for the SOHC 95-99 neon engine 420a is the version we have in the eclipse/avenger/sebring platforms.
No, A588 is the code for the 420a motor period. Just like there are 420a sohc, dohc 2.4 dohc. A588 is just a designation as broad as "420a"
To say its one or the other is wrong, its all of them.