Trademark vs. LLC name — do I need both?

Formed "BrightPath LLC" in Delaware. My product is called "BrightPath." Someone said I should also file for a trademark. But doesn't forming the LLC protect my name? What's the difference?

Very common confusion. They're completely different things:

LLC/Corp name registration: Just means no other LLC in that state can have the exact same name. Doesn't stop someone in California from forming "BrightPath LLC" or someone else from using "BrightPath" as a brand.

Trademark: Protects your brand nationally in your specific industry. Stops others from using confusingly similar names in commerce.

Short answer: yes, you probably want both.

wait so I could form "Nike LLC" in Delaware?

You could probably register the LLC name (if it's not already taken in Delaware), but if you used it in commerce, Nike would sue you for trademark infringement and win. The LLC name registration doesn't give you the right to actually use the name.

how much does trademark registration cost? just trying to understand if this is a $100 thing or $10,000 thing

DIY filing: $250-350 per class (USPTO fees)
With attorney: $1,000-2,500 total including search and filing

I generally recommend using an attorney for the search at minimum. The last thing you want is to build a brand for 2 years then get a cease & desist because you didn't find an existing registration.

That makes sense. When should I file? I'm pre-launch, just building the MVP.

Do a clearance search NOW before you invest more in the brand. Costs $300-500 and tells you if the name is likely available.

For actual filing, you can file "intent to use" before launch or wait until you're using the mark in commerce. Intent-to-use is more expensive but locks in your priority date earlier. For most startups, I recommend waiting until you're actually selling something.