rdesktop is an implementation of a client software for Microsoft's proprietary Remote Desktop Protocol (RDP).
License: Open Source
UltraVNC is a versatile remote desktop solution with extensive features, including file transfer and cross-platform support, while rdesktop is optimized for lightweight performance in Linux environments but lacks some advanced features. Users should choose UltraVNC for rich functionality and cross-platform needs, whereas rdesktop is ideal for straightforward remote access on Linux systems.