You really ought to follow all the links to full descriptions, because the answer isn't a simple yes or no. I'll sum up a little, but this run-down is NOT comprehensive:
EQ is 100% free up to the penultimate expansion, with limits on extras like wealth, inventory, AA, available classes, guild formation. So entirely without paying, someone can download & install the game, make a core-class character (cle/war/rog/wiz), play in the real zones up through House of Thule including all the awesome old content of Basic/Kunark(+addons)/Velious/Luclin/PoP/LDoY/LoY/GoD/OoW/DoN/DoD/PoR/TSS/TBS/SoF/SoD/UF (for those keeping track at home, this was a decade of content for paying players), with all the paid subscribers, advancing to 90 with a handful of AA.
A one-time, permanent $5 upgrade to "Silver" (given automatically at no cost to everyone who has ever paid anything for EQ ever in the past) upgrades the account to allow more characters, more wealth, quadruple AA cap, more classes, looser guild rules, etc.
"Gold" membership (all current subscriptions became this today) is entirely equivalent to how EQ has been played & paid for in the past, with a toss-on benefit of 500SC per month included in the subscription price. That 500SC/month that they now get without paying any more is the only difference current payers/players will see in EQ, besides, hopefully, a boatload of n00bs to play EQ with