A logo is a single mark: the symbol, wordmark or combination that identifies your business. A brand identity is the system around it: the color palette, typography, graphic elements, photo style and the rules for using them together. The brand itself is the impression people form through that identity, your messaging and the experience you deliver. Logo design services give you a file. Brand identity design gives you a system that keeps a proposal, a social post, a sign and a website looking like the same company, even when different people produce them.
A complete identity typically includes primary, horizontal, stacked and icon versions of the logo; a color palette with print and screen values; a type system for headlines and body text; and supporting elements such as patterns, iconography and photo style. The logo is designed to work at every size, from a tiny app icon or social profile picture to a large sign.
Before any of that comes brand strategy: who you are, who you serve and why a customer should choose you over a competitor. Discovery and positioning are what keep the design from becoming a matter of taste. After the system come the applications: business cards, letterhead, social media templates, website look and feel and presentation templates. Applications turn an identity from a folder of files into something your team uses every day.