I've been thinking about these two words quite a bit, since a student used them in a paper, interchangeably. And they're not twins/synonyms, they can't be used in place of the other.
Yes, it's complicated and complex. I'll try and decipher the difference.
Complicated - Today's schedule - workout early this morning while wanting to sleep, hospital, UVU, chaplain meeting are the logistical issues, with patient visits, chaplain meetings, papers to grade, papers to write, whiny students to listen to, finding an LDS employee to give a blessing, volunteer appreciation day and Admin appreciation day gifts and kind words, stay bright and cheery on 6 hours of sleep, directions for roasted veggies to Scott, field chaplain calls that are not mine to field - in kindness, order cake for party tomorrow night, and have the energy and serenity to oversee a meeting this evening. And lunch with Tom and Jenna.
Complex - My breast pain scare - anxiety it produced, that still hasn't totally left me. Sorting out in my mind what is truth, what is real, and what that truth and reality mean. Attempting to keep this from my loved ones, so I don't have to explain the complexity of my fears. I can't explain the unexplainable.