Default: After adding license to the server farm, the Default load evaluator is attached to each server in the farm.It contains two rules: Server User, which reports a full load when 100 users log on to the attached server and Load Throttling, which specifies the impact of logging on users to the server and limits the number of concurrent connection attempts the server is expected to handle
Load Throttling
Limits the number of concurrent connection attempts that a server handles. This prevents the server from failing when many users try to connect to it simultaneously.
The default setting (High impact) assumes that logons affect server load significantly. This rule affects only the initial logon period, not the main part of a session.
The Load Throttling rule can be applied only to a server, not to an individual application.

Advanced: This load evaluator contains the CPU Utilization, Memory Usage, Page Swaps, and Load Throttling rules.
We cannot delete the Citrix-provided Advanced or Default load evaluators and can create new load evaluators based on the rules available. Each server or published application can have only one load evaluator attached to it.

qfarm /load command displays the load for all servers in the farm

The qfarm /app command displays the load for all applications and servers in the farm. The load, 99999 means there is no load evaluator assigned to the application.