Process Explorer : Details vs Column "Read Bytes"

Process Explorer seems to offer two ways to look at "I/O Read Bytes". One is to add the Column from the "Process I/O" page, another is to use the 'same' column from "Process Disk". What is the difference? It seems the second one only shows values since last start of PE?

Also, the second value can also be looked at from the Process Details, but the first one can not, as it does not show up in the "Performance" Tab.