The two 的 are different, if you want a precise answer. BUT 的 is used flexibly. It literally means possession, location, etc. And you can regard the concept LOCATION as an abstract "possession" in Chinese... Examples: 我的家 my house (house of mine) 我的朋友 my friends (friends of mine) 房子的右边 the ride side of the house 我的左边 the left side of me 桌子上的台灯 the lamp on table (seems like the lamp of table ... =） But this sentence also has a word 上, which means "on". And 的 here is an indispensable part of FIXED COLLOCATION. 天上的白云 the clouds on the sky (similarly, clouds of sky ... maybe it doesn't make sense in English but anyway ... ) But please attention lots of English words can be translated into 上 followed by 的, like above... 楼下的花 flowers down the building ( ...now you probably know why 的 here, 下 means "down" and 的 is part of fixed collocation, and you can regard the LOCATION as somewhat "POSSESION" in Chinese） 路的前方 the front of the road 路的尽头 the end of the road 桌下的书 the book under the desk ...... hope it's helpful~

hi Alberto, you are right, you can consider it as a possesive marker im most situations. So there is always a noun on the right side of 的. the word or phrase on the left of 的 decorates the one on the right side.

the right sides of house = 房子的右边