高级 (gāojí) is a broad word for 'high-class, advanced, senior' — it can describe quality (高级餐厅), skill level (高级课程), or rank (高级工程师). Contrast with 先进 (xiānjìn), which focuses on being progressive in technology or ideas, and 高档 (gāodàng), which is limited to high-grade products or goods. For people with experience, 资深 (zīshēn) is more common.