Pixie and Citiz are two different Nespresso machine models. The main differences between the two are their size and design. The Citiz is slightly larger and has a more modern, sleek design, while the Pixie is more compact and has a retro-inspired design. In terms of features, they both offer programmable cup sizes, automatic shut-off, and the ability to make both espresso and lungo shots. However, the Citiz also has a built-in frother, while the Pixie does not. Ultimately, the choice between the two will depend on personal preference and whether or not you prioritize size or functionality.