Differences Between CONTOUR and CONTOUR2
CONTOUR2 enhances PV‑WAVE’s contouring capabilities by adding scattered data plotting and sophisticated curve smoothing to produce more realistic contour lines than CONTOUR. These advantages are especially noticeable in smaller data sets.
When to Use CONTOUR2
Use CONTOUR2 to plot 3D scattered data. Note that CONTOUR2 plots rectangular and irregularly gridded data using the same curve smoothing algorithm that it uses for scattered data. CONTOUR2 produces more “realistic” contours, especially for sparse data sets. CONTOUR2’s Fill keyword simplifies the procedure for creating filled contours. When to Use CONTOUR
Because CONTOUR2’s curve smoothing is computationally intensive, consider using CONTOUR if a shorter computing time is important. Remember that whenever you use CONTOUR, your data must define either a rectangular or curvilinear coordinate system.When to Use either CONTOUR or CONTOUR2
For regular or irregularly gridded data, you can use either the CONTOUR or CONTOUR2. 
