When in top, typing capital "E" cycles through different memory units (kib, mib, gig etc - which are different from kb, mb and gb) in the total memory info:

![The image shows tops general memory display with GiB as a unit.][1]

While lower-case "e" does the same individual process lines:

![The image shows processes in top where the memory is displayed in MiB][2]

From the manpage:

 2c. MEMORY Usage
 This portion consists of two lines which may express values in kibibytes
 (KiB) through exbibytes (EiB) depending on the scaling factor enforced
 with the 'E' interactive command.

*Version Information:* `top -version`: `procps-ng version 3.3.9` *System: CentOS 7*


 [1]: https://i.sstatic.net/PKIa8.png
 [2]: https://i.sstatic.net/9tzqE.png