My understanding is the following: No-prefix < Senior < Staff < Principal. In details, I see it this way: No-prefix: focuses on the here and now with little r

My understanding is the following: No-prefix < Senior < Staff < Principal. In details, I see it this way: No-prefix: focuses on the here and now with little responsibilities about long term strategy/cooperation with other teams. Senior: he/she can be/is a TL. Sets the direction for the team and thinks about medium/long term strategy/shape of the code base. Also, they tend to be the liaison between the team they are under and other teams, but in a tactical/ad-hoc way. Staff: Like senior, but more on the strategic side of things (i.e. longer term planning). Principal: Usually the TLM/uber TL for a working group (few teams). Can also be a director for a working group. As pointed out by other replies, It is subjective and also company-dependent. In startups these levels tend to be compressed, in FAANG companies there's a distinct increase of responsibilities with each title.