Hello Which one of the stated version is the lighweight or more modern for a 4 GB RAM i3 processor laptop
Both are LTSB and get serviced for 10 years, so 2015 LTSB is almost done and 2016 LTSB next year, Both are LTSB so both don't have the store and anything related like apps. Both are very low on resources because they are OLD, from a simpler time and less spec hardware. Your i3 could run Enterprise 2019 LTSC or 2021 LTSC just fine, which is supported till 2032 when you use the IoT Enterprise 2021 LTSC version..