The meanings are almost the same but they feel very different and it truly does matter which one you use. Infinitives are factual, but present participles are descriptive. There is little to say about the infinitive. Infinitives say exactly what the dictionary says they say. So "it is easy to see you" means it is not at all difficult to SEE you. If you know what the verb "to see" means, then you understand the sentence. Present participles are a different story. They do not mean what they say. Ask this question on iTalki and you will get many different answers. Different people think about the participle in different ways. Some teachers will tell you a story about continuous happenings or something like that. Others will tell you a different story. Whoever you talk to, you will not end up understanding the meaning of "seeing". That's because the present participle represents the meaning of the verb "to see" as it can be IMAGINED, and different people will imagine it in different ways. I think of present participles as photographs. If you say to me "It is easy seeing you from my house" a picture immediately forms in my mind of you looking out of your window towards my house. The present participle makes me see this picture. This is why present participles work better than infinitives in friendly conversation, whereas infinitives work better for stating facts.