The DS2401+ and the DS2401A+ are both 1-Wire "Silicon Serial Numbers" available in different chip packages. These 1-Wire chips are the heart of what's inside the DS1990A-F5+ and DS1990AA-F5+ iButton devices respectively.
Are the DS2401A+ and DS1990AA-F5+ automotive grade?
The short answer to this question is no.
What are the DS2401A+ and the DS1990AA-F5+?
The DS2401A+ (the heart of the DS1990AA-F5+) is a variant made on a different semiconductor manufacturing process to help with the chip shortage. Changing to the new process should ease the supply.
What are the differences between the DS2401+ and the DS2401A+ (which are the same between the DS1990A-F5+ and the DS1990AA-F5+)?
These chips are very similar and could be used as a replacement or "near" replacement for one another. But, as always, please realize it is in the customer's best interest to thoroughly test and qualify the DS2401A+ or DS1990AA-F5+ to make sure it works as desired in their application.
The DS2401A+ is different from the DS2401+ in a few different ways (most of them relatively minor). Here are the differences as reflected in the data sheet of the DS2401A+ (which is pretty much the same ones in the DS1990AA-F5+). See the screen captures of the data sheet below (with differences highlighted in yellow):
Image 1. Differences in 2 ROM function commands (page 5 of the data sheet)
Image 2. Electrical Characteristic Table on page 10 of the data sheet