Now here's an idea that many will find strange. Could it possibly be that it is easier to learn Mandarin than Spanish? I think the answer is, "it depends." Obviously, the writing system for Mandarin is incredibly complex. You have perhaps a couple hundred pictographic characters that are somewhat similar to hieroglyphics, but after that you've got to memorize thousands of characters that don't look like what they mean. If you bring the writing system into it, Mandarin is easily one of the hardest languages to learn.
But what about only speaking it?
This is where Mandarin may have a huge edge in ease of learning.
Mandarin is a tonal language. There are four tones in the language, which come across as very difficult. And I agree, they are difficult. But the good news is that, in terms of speaking, that is your primary challenge. Because of tones, Mandarin uses the same words over and over again, using a different tone to differentiate words. This is very efficient in a way and is why to a non-Chinese speaker, Chinese can all sound the same. Spanish has tons of cognates with English, but there are also lots of false cognates. Chinese surprisingly does have a few cognates with English. And as far as I know, there are no false cognates.
But if you can master tones, it isn't that difficult to actually speak Mandarin.
There are no conjugations and no tenses! This makes it incredibly easy to speak without messing up.
Compare to Spanish, which has lots of conjugations and tenses, and if you compare only speaking the languages, Mandarin is probably easier to learn.
So, let's look at an example:
English: I am going to school.
Spanish: Voy a la escuela.
Mandarin: Wǒ qù xuéxiào. (Literally: I go school.)
In Mandarin, you don't have to worry about the tense or conjugation. You need a subject, verb, and object. Throw them together in the same order as English and you're making sentences in Mandarin easily.
-Tons of cognates with English
-Uses Latin alphabet
-Tons of conjugations
-Complex grammar like all European languages
-Recycled words mean a smaller pool of vocabulary to learn
-Complex writing system
Most people, I think, shy away from Mandarin because of the writing system. But only speaking Mandarin is probably easier than speaking Spanish once you can master tone usage.
Re: Is Mandarin Chinese easier to learn than Spanish?
I have to amend something I said earlier: apparently, Mandarin DOES have tenses...sort of. You can indicate when something took place by placing the words, "yesterday," "today," or "tomorrow" at the start of the sentence.
You can also wrap verbs in "guo" and "le" in order to say something happened in the past. I don't understand well how to use this, though. But I think you just put the verb in between the two words.
Anyway, it was silly of me to say earlier that mandarin has no tenses. Even if it had "none," it would still have a present tense. I don't think it is possible for a language to have literally zero tenses.
I would say the difficulty of learning Chinese characters would be eased significantly if one learned how to learn it in the traditional manner. Which is through constant reading and writing characters over and over again, starting by picking up a pen. So I don't think the problem of learning Chinese is about simplified vs traditional, since I learned traditional characters in my youth. Writing in Chinese became second nature to me, even though I'm going to brush up on Mandarin again because I'm going to need it.