Illustrator exported blurry JPEG

So I am new to illustrator and am trying to create a portfolio. I made a logo to put on my website and when I export the logo to jpeg or png (dont quite know what the difference is, just read online to do that lol) it comes out blurry and pixelated.. I chatted with someone on adobe support and they helped me turn it to the highest quality and it still looks slightly blurry. Anyone know how to fix this? I am desperate...

I also have several other questions if anyone would like to help me and tutor me in this haha

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