The difference between both Array formats
Using the ARRAY custom field on Honeycommb you can either decide if you'd like the field to be a multiple check-box or a single select radio button. Visually and functionally to the user, the two fields are different: 
Array Single-Select:
Using a single-select, users are allowed to select only ONE option as a radio button from the list of provided answers.
Array Multi-Select:
Using the multi-select, users are allowed to checkboxes from a drop-down list of possible answers that they can use to indicate results to an answer.
TIP: When creating an array, you can make the selection for either of these two different formats by using the validations section in the field editor creator.
Array Single-Select:
You'll want the validation for maximum length to equal 1
Array Multi-Select:
The maximum is not required to have a multi-select. If you add maximum value, then it will still be a checkbox but users will have the ability to select the max amount of checkboxes provided. 