Difference between sexual and asexual spore
In the same wikipedia page of spores you cited, you can find that they have said:


  Fungi commonly produce spores, as a result of sexual, or asexual, reproduction. Spores are usually haploid..


Again,


  Vascular plant spores are always haploid. 


So, sexual and asexual spores have no difference in ploidy- both are haploid. (There are exceptions- zygospores in fungi are diploid)
Now, coming to mode of formation, they are different. For example, in Ascomycetes, sexual ascospores are produced endogenously whereas asexual conidiospores are produced exogenously.

Spores that are formed by the process of meiosis are sexual spores and when formed from mitosis are asexual. The term 'sexual' means meiosis is involved.