Telegram does have E2EE in secret chats. WhatsApp does NOT have E2EE because it backs up your private keys to cloud storage by default. Even if you don't, your contacts might. Therefore WhatsApp is less secure.
This is incorrect. WhatsApp is E2EE as well. It does not backup the keys to their cloud. Rather, you seem to be referring to the fact that they offer cloud backup on Google Drive, in which case the chats are stored in plain text.
You're being unnecessarily pedantic and not actually even refuting anything they said.
Using Whatsapp is like sending a locked chest to your friend and a copy thereof + a copy of the key to unlock it to a warehouse. Government employees and warehouse workers can enter the warehouse at will, use the key to open your chest, and copy everything too.