I am confused on how cold wallets and hot wallets differ. To make any transaction we still need to get access to internet. Then how are they different?
Being connected to the internet makes the wallet hot and every wallet needs to connect to the internet for any transactions.
Cold wallet is only needed to sign the transaction.
For example you generate the transaction on a view-only wallet (based on the address, not on private key), which stays online safely, transfer with an USB stick that transaction to the cold wallet (offline) computer, sign it, go back to the online computer and dispatch it.
However, if you only store your Bitcoin and don't plan to spend, (safely generated!) paper wallet is cheap and pretty safe. And you can always send more Bitcoin to that, you can always check the balance safely online and, as long as you keep your private key safely and privately on a piece of paper nobody else can spend your coins until you import the private key into a wallet.
Ah I see. So basically hard wallets would be more secure than any online applications or software.