Transfer is digital or physical sharing - if I transfer something to you, you now have some kind of ownership or power over whatever I transferred. E.g., if I transfer some notes to you, you are then able to change what the notes say (or at least on your copy) or a least otherwise have some possession of them. Assign doesn't need digital or physical sharing. You can be assigned a piece of work to do without ever having any copy of the work. But it does also mean to change ownership. My guess would be that the contract is covering all possibilities. It's both forbidding giving the agreement away to a third party by any means, either legal or physical. So you can't give someone else a copy without them owning it, but you also can't allow someone else to own it (or otherwise have control over the agreement).

Nanren888’s answer is best. It’s specific legal wording and you can’t guess the full meaning from a casual knowledge of English. “Assign” and “transfer” have different meanings and the contract covers both possibilities. It’s a very common wording in US contracts.

@Michael Smith: You're always the one who brings the best answer for me. Thank you so much. I've taken a look at the link you've attached. The material is super useful :). Have a nice day Michael. Thank you once again.

In much legal writing there is an effort to cover all possibilities and remove any possible areas for future dispute. If there is a distinction between "assign", "transfer", and "otherwise dispose of", this contract attempts to mitigate that difference. These links might help, if you want to explore - but be aware that the contract will (probably explicitly, if between parties in different countries) be governed by one or anotther specific set of national law - and you would need to check details of that specific country's law. https://www.upcounsel.com/difference-between-assignment-and-transfer https://assignments.uslegal.com/distinction-between-assignment-and-other-transfers/

@Naren888: Thank you so much for your wise advice :). I see. I have searched for its meaning in an online legal dictionary but it seems to be unclear. I try asking for the native speaker's thought.