They are both very close. The Holiday Inn Universal is directly across Kirkman from the Universal parking garages near the Major Blvd. traffic light. The Fairfield Inn is one block further north near the Vineland Road traffic light. If you're at all familiar with the Kirkman area, the FI is behind the Ponderosa across Kirkman from the Portofino Bay Hotel. We have stayed at the Fairfield Inn Universal and I give them a very good recommendation. If you have a car with you, both locations are very close. If you are attempting to walk to US/IOA, the Holiday Inn would be a bit closer. Keep in mind that any of the hotels located "across the street" from Universal will still require at least a 20-25 minute walk to get to the park entrances. I believe both hotels have shuttles to the parks but I can't offer any comments on them in that we had our car with us and just drove to the parking lot. (Less than 5 minutes.)
Hope this info helps you out. Have a great time!