Biggest difference is that Levimir release cycles
last around half as
long as Lantus, which makes for 2 basal shots a day, and it's a little easier to accidentally overlap doses. For example, I try to get my shots at 7am and 10pm, but that creates a 3-hour overlap and gap on either end.
Getting the dosage right makes it easy to work around, but it's only as good as the consistency in your schedule.