Understanding and comparing the evolution of public opinions on a social media event is important. However, such a task requires summarizing rich semantic information and an in-depth comparison of semantics and dynamics at the same time, which is difficult for the analysis. To tackle these challenges, we propose ContextWing, an interactive visual analytics system to support pair-wise comparison for evolving sequential patterns of contexts between two data streams. The computational model of ContextWing generates dynamic topics and sequential patterns, and characterizes public attention and pair-wise correlations. A novel multi-layer bilateral wing metaphor is designed to intuitively visualizes sequential patterns merged by different contexts to reveal the similarities and differences in both temporal and semantic aspects between two streams. Interactive tools support the selection of a central keyword and its contexts to iteratively generate patterns for a focused exploration. The system supports analysis on both static and streaming settings that enables a wider range of application scenarios. We verify the effectiveness and usability of ContextWing from multiple facets, including three case studies, two expert interviews, and a user study.