It is really not easy to tell, we normally use 庭with other characters ,eg，法庭.

庭院normally means ancient buildings ,or modern building looks like old one.

Hi! 庭: courtyard, garden, front yard. 園: field, plantation, garden, park. Both mean garden, and as you know, a garden is an outdoor planned space, that is set aside for cultivation of plants and flowers. They can range from small to very large sized ones. 庭 is common to use for small gardens or small fields like the front yard of a house or the courtyard of a building. 園 is a garden, but a relatively large one. You can find this Kanji character in words like 公園 which means park. As you know, a park is could range from a couple of square miles to several thousands of square miles. 庭園 is a small or medium-sized garden which can be found in houses, villas, etc.