This means that the owner of the address can only spend his coins after the block 500103. People tend to do that to "prohibit" themselves from spending their coins until a certain date.
The first transaction is a regular one, so there is no time lock.
A Timelock is a type of smart contract primitive that restricts the spending of some bitcoins until a specified future time or block height. Timelocks feature prominently in many Bitcoin smart contracts, including payment channels and hashed timelock contracts. It can also be used to lock-up bitcoins held as an investment for a period of months or years. Time lock is also used to make fee sniping less profitable.
https://en.bitcoin.it/wiki/Timelock
