I would expect the "jibberish key" is the address in this case. The set of words is known as a "seed", and is used to back up all the private keys in your wallet. NEVER share those words with anyone, anyone with those words can spend all your bitcoins.

"Normal" bitcoin addresses start with a 1 and are usually around 34 characters long, made up of lowercase letters, uppercase letters and numbers. An example is 1BvBMSEYstWetqTFn5Au4m4GFg7xJaNVN2. Some bitcoin addresses also start with a 3. More recently a new type of address has begun being used, starting with bc1, but its unlikely you will see these commonly for a while. These addresses are all anyone needs to send transactions to you, they will never need the seed words or the private keys or anything else. Keep those safe and to yourself.

Some wallets such as blockchain.info also use a wallet identifier which is made up of numbers, letters and dashes (-), that is also for private use and does not need to be shared, it is not an address.

First off, and importantly: DO NOT EVER share the list of words. Do not even type it into a computer, take a photo of it, or otherwise store it digitally. This is SERIOUS. If it exists digitally, someone could steal it, and then your bitcoins are gone. Write it down with pen and paper, and store it somewhere really, really safe. If you have already stored those words digitally, then just forget about that wallet, and make a new one right now before you transfer any coins.

Now then: A bitcoin address has two keys associated with it: a private key, and a public key. The private key lets you spend the coins, so you must keep that safe! The public key is something you can share with others, so that they can pay you.

So, in your situation, the list of words is the seed for your 'master private key'. It is actually just a big number, encoded into a string of words, and the wallet software uses it to create a 'master key' to generate all subsequent addresses in your wallet. Keep it safe!

Your wallet uses the public key to generate a bitcoin address, which is a string of random-looking characters. It should look something like this: 1L3AqyJm6tdt8SNFKJ4D7cLqQP8V7ihbpR (random address from a recent block). This is what you need in order send a transaction.

One last note: every time you receive a transaction, use a new, unique address. Try to never use the same address twice, your wallet will continuously generate new addresses as needed. Not reusing the same address is very important in protecting your financial privacy.