Both of these suffixes are added to nouns to make an adjective that denotes that something has the qualities of the noun, e.g.
적(이다)
역사 history → 역사적(이다) historical
세계 world → 세계적(이다) worldwide
전통 tradition → 전통적(이다) traditional
스럽다
사랑 love → 사랑스럽다 = lovely
자연 nature → 자연스럽다 = natural
Are there any rules or guidelines as to which ending to use? Are there any words with which you can use either ending?
I see that you quoted the examples from this site:
http://www.howtostudykorean.com/unit1/unit-1-lessons-9-16/lesson-16/
If you look at the wordings in detail, it already explained that you CANNOT identify which one, 적 or 스럽다 can be used if you never met that word.
However, there is one characteristic for 적이다/적으로. 적 is the hangul of 的, which is a possessive particle in Chinese. So the word before 적 has to be originated from hanja.
Example: 세계적(世界的), 전통적(傳統的), 역사적(歷史的), 일반적(一般的)
There are of course exceptions for hanja characters, namely 자연(自然)스럽다, 실망(失望)스럽다, 만족(滿足)스럽다
But this confusion only happens in Hanja originated words, for non-hanja words, you could only use 스럽다 and never 적이다.
Example: 사랑스럽다, 자랑스럽다, 짐스럽다
I don't think there are any words which can be added both endings. If you see one, just memorize it.
