RapidBlock will capture multiple buffers to the scopes internal memory with minimum dead time between buffers (~1usec) and automatic rearming of the trigger. The limit to how many buffers you can capture will be the size of each buffer compared with the memory depth of the scope. You then download the complete set of buffers from the scope for analysis. At this point you can then restart another set of captures.
Block mode will not automatically rearm the trigger, this needs to be handled by the application after the previous buffer has been downloaded from the scope and can lead to a rearm time between 1 and 60ms. The actual value will be dependant upon the PC, other USB users, and operating system overheads and will vary buffer to buffer.