They are the same, but you shouldn't trust any of them, even if we agree that big sites like poloniex or coinbase are honest and their owners don't intent to run away with the funds the danger of gettimg hacked is always there.
Any hard/paper/desktop wallet is safer than them,all you need to do is to follow some basic rules and keep your private keys well hidden.
You are forgetting to mention blockchain, this is what the bitcoin technology depending to with the so called blockchain technology.
I only use exchanger's wallet to store altcoins which i get from avatar campaigns,etc. I find it easier to use a wallet of new currency instead of installing the same on my pc. So far i have no problem with using yobit's wallet.
Depending on how you are going to trust an exchangers security then just save there at your own risk. Because out of the bitfinex incident, for sure many are doubtful on this.
But with me, I am using and storing my bitcoins with a local exchanger, because offline wallets are much more risky for me.
Because here in my place a lot of robbers will put interest to the things that they just see new in their eyes, even my relatives.
Wow, even your relatives?
Many people don't trust the exchange wallets because in the past some of those exchanges closed or were hacked and traders, investors lost their money. The exchange owners aren't very very trusted and unexpected things happen. So better to don't risk our money on it using an exchange as wallet.
Yes that's true, because I have tested them for so many times that I am able to leave my physical wallet to our table, not knowing that it is just my bait.
After a couple of minutes, my physical wallet gone when some of my relatives came into our house and asking us if we have food.
So after giving them food, they took my wallet also.