@kristapsk pointed out that the first whitepaper was not made public on January 14, 2016, but in February 2015. The only thing I've been able to ascertain is that the latest version (DRAFT Version 0.5.9.2) is a more detailed version. The official Lightning Network website doesn't mention this fact and that's what misled me.

Thanks @kristapsk for the correction.

🔗https://lightning.network/lightning-network-paper-DRAFT-0.5.pdf

Don't miss: https://voltage.cloud/blog/bitcoin-lightning-network/life-of-lightning/