I agree with @Heather S. : trying to learn two instruments with widely differing embouchures at the same time sounds like a terrible idea.
I worked at a band instrument store for over eight years. One thing that I found for beginning students is that, for at least some students, there is a natural aptitude for one type of wind instrument for another. For example, it is much easier for me to get a sound out of woodwind instruments (like the saxophone) than it is for brass instruments (like the trumpet). The only way to find out if you have an innate aptitude is for you to try to make a sound on both. Find a local band instrument store with a good reputation; they should be willing to let you try both before you make a decision.
I don't know how music stores operate in your country, but perhaps starting with renting an instrument would be better. That way, you start with one, and if/when you find out you don't like it, you can switch to the other, depending on the store's policy.
RE: difficulty, I personally believe that all instruments are relatively the same level of "difficulty" to play; while trumpet might have a slightly more difficult embouchure to master, until you get start to master your trumpet playing, a saxophone player is going to be expected to be able to play WAY faster than most trumpet players ever could, especially in jazz (I'm speaking in generalities here).
Finally, no matter which instrument you pick, one thing that I found anecdotally while working at the music store was that the bigger the mouthpiece is, the easier the instrument is to play, e.g. tenor sax is easier than alto, and baritone sax is easier than tenor; baritone/trombone is easier than trumpet, and tuba is easier than baritone/trombone. Just something to think about.