i was looking for the word meaning to be lit which is 付く but as a looked at the meaning it said to see 点くwhich i found to also mean 'to be lit' so are they both the same or are they different? and can i use them both in any case or are there exceptions? thanks for any help and sorry for my frequent questions
There are words which can be written using different kanji. In your example, 付く can be used for a variety of meanings, one of them being the same as 点く. The first is a very common verb and is many times used as a suffix to other verbs. The latter is specifically for saying something is lit or catches fire.
These meanings can easily be differentiated by looking at the meaning of the words in the dictionary. But, there are several more verbs with the same relationship, in which the dictionary would show the different ways of writing the same word to have the exact same meaning. Take 見る for example. It has the same relationship with 看る as 付く has with 点く. But the dictionary shows 観る and 視る (miru and miru) to simply be different ways of writing the verb 見る. Although this is true, these different ways of writing do have an emphasis on usually one of the meanings of 見る. To determine what's the emphasis, you have to look at the meaning of the kanji used for that writing (and usually at the context of the word too). 視 means "inspection". 視る will thus have one of the meanings of 見る with an emphasis on that.
That's for the kunyomi writing. Words read with the onyomi writing can be written with different kanji and have the exact same meaning. In literature the author might use the different kanji in a way to produce the right feeling of a word for his work. It's not similar to the kunyomi's "emphasis" stated above, but is purely aesthetic. There are also a lot of outdated kanji which you should ignore for now (or forever).
I don't disagree with holyeyeolo's answer, but I want to suggest a slightly different way to look at.
First off, drop the word "word" with respect to this problem. Instead, let's split things into:
- orthography = how we write something down.
- pronunciation = how we say it.
Now, I'm going to tell you a myth. A long time ago there was a language called "old Japanese" that was spoken (it had a pronunciation) and it probably did not have a writing system of its own before then (see here).
Then, the Japanese imported kanji (multiple times actually) as a way to write (and developed kana from the kanji as a way to write down pronunciation).
So they had something pronounced "miru" and they matched that to several Chinese characters for slightly different meanings of miru: 見る、観る、視る、看る. As time passes, two related things happen. First, people begin to think of a kanji when they are saying "miru" (and thus they are no longer just thinking "miru"). Second, people start to wonder whether they need two different characters in some cases or if one is fine. (One version of the second one is that the Japanese government maintains a list of kanji that it thinks people should know/use).
These two forces collide in every case and result in three basic patterns:
One kanji is general and the other ones are subsidiary: 見る vs. 観る、視る. I could be wrong but my sense is that you usually won't be wrong but won't always seem erudite if you always use it. e.g. 映画を観る is better than 栄華を見る or so I'm told. (See https://kotobank.jp/word/%E8%A6%8B%E3%82%8B%E3%83%BB%E8%A6%B3%E3%82%8B%E3%83%BB%E8%A8%BA%E3%82%8B%E3%83%BB%E7%9C%8B%E3%82%8B-392966. There's technical contexts where only one is appropriate, but you'll be completely safe when speaking!) (看る has a meaning of "to look after / attend to" and doesn't seem to fit this pattern)
Two (or more) kanji remain on equal footing but it's important to know which one to use in different circumstances, because the meanings are seen as pretty different at this point. 票 vs 表 or 表す vs 現す.
Several kanji exist, many of which are specialized, such that there's no "safe" kanji to pick when unsure so people including native speakers end up using the kana, for instance とる. (取る、撮る、採る、捕る ...). Many of the different kanji have a specific use, but good luck with that (https://kotobank.jp/word/%E5%8F%96%E3%82%8B%E3%83%BB%E5%9F%B7%E3%82%8B%E3%83%BB%E6%8E%A1%E3%82%8B%E3%83%BB%E6%8D%95%E3%82%8B%E3%83%BB%E6%92%AE%E3%82%8B%E3%83%BB%E6%91%82%E3%82%8B%E3%83%BB%E8%84%B1%E3%82%8B-344420 , https://www.nhk.or.jp/bunken/summary/kotoba/uraomote/111.html)
Are these different orthographys for something pronounced in the same basic way, different "words"? I think that depends on how much of the two factors post-import have happened. (I'm having trouble finding it but there's a question somewhere on this SE about what a word is in Japanese where several of our native speakers contributors show how hard that is to answer)