Junior devs on the other hand tend to be developers with little to no experience with some of the core technologies used within the role. Typically they'll require some help from more senior devs to get up to speed.
I've been a developer for over 10 years at this point and I'm not really sure I feel like a senior dev. Every week I'm reminded how much I don't know. There's definitely a huge variance in the abilities of senior devs. Some of worked with are been terrible while others have been indispensable to the team. It's always bothered me that variance wasn't reflected in pay or title.