Bogleg got you set, a cob is just one type of led. It’s also used generically a lot, but nobody I know of here is gonna bust your balls over something trivial like that.
You don’t necessarily need to use cobs to get good leds either, that was just an example. Quantum boards are really good, and there’s some led strips that you can diy as well.
Figures, trying to grow and get help but my post was rejected for a link because i’m new. SMH not to mention carpal tunnel surgery. This is a 5 min post for me.
Besides brand name COBs (chip on board) there are also strips (of LEDs) and individual high-power LEDs. Some companies put individual LEDs on their own boards that they then sell to you. These can approach 200 lumens per watt, if you don’t drive them too hard.
Then their are Amazon blurple lights, Chinese COBs, general lighting LEDs in a fluorescent tube, LED spotlights, and LED light bulbs. These are all much less efficient. More like 50-70 lumens/watt. They may seem cheap, but not for the amount of light you get and not over the long term considering you pay twice as much or more on your electric bill. In fact, they lose to HPS at 133 lumens per watt.