Traditional domain names are limited to a combination of English letters and decimal numbers. The only symbol character domain names can include is a hyphen (-) though the domain name cannot start or end with a hyphen nor have consecutive hyphens.
Handshake names can be quite literally anything, from English letters and decimal numbers to Chinese characters and even emojis!
A top-level domain (TLD) today requires a $185,000 application fee to ICANN, which may or may not get approved, on top of an auction fee which can cost millions.
Anyone can bid on a Handshake TLD without a fee and win it through the decentralized auction process — the market and the auction demand determines the price of any given TLD, not Namebase or Handshake.
All of the ~1,500 TLDs that already exist in the ICANN root zone (e.g. .com, .org, .io) are reserved and cryptographically claimable by the owners of those names for backwards-compatibility. This means that end-users resolving their DNS through Handshake can still access .com domains as normal. New ICANN TLDs can theoretically conflict with Handshake TLDs, but ICANN isn't issuing new TLDs for another few years. When ICANN does issue new TLDs, they’ll only allow at most 500 new TLDs per year.
Additionally, the top 100,000 most visited websites as determined by Alexa are also reserved for their owners (e.g. owner of Bitcoin.com gets the name “bitcoin” on Handshake, and Google gets “google”) — see the full list of already claimed names here.