Confidental Transactions from Blockstream hides the values of a transaction so business privacy is retained. CN doesn't do this.
It does to some extent because there are multiple outputs with some being change and some being payment (or payments). How they are grouped is not visible, so combinatorially this can give reasonable privacy of the payment amount. The choice of outputs affects how much actual privacy there is in practice and the current algorithm in Monero is not great, but is being improved.
As for size I gather that CT and CN are similar but I haven't reviewed it carefully.