When viewing transactions or entity records in NetSuite, one will find the New Task and Log Task buttons under Communication tab > Activities subtab.
New Task button is for creating tasks done on a future date or a scheduled one.
Log Task button is for creating tasks for tracking or recording purposes only and is not used for scheduling (no Due Date field).
If a task has already been completed but not yet recorded, Log Task should be used instead of New Task.
Below is a table that will show the fields available in the main section of a Standard New Task and Standard Log Task forms:
New Task Form
Log Task Form
Notify Assignee by Email
Note: Availability tab is not present in Log Task forms.