mirrorless:

DSLR:

Mirrorless are generally smaller than regular DSLR and packs almost all features of a DSLR in a smaller, compact body. Both has their own pros and cons. The article below basically has almost all basic aspects covered to help you understand and decide which one you need.
http://www.tomsguide.com/us/dslr-vs-mirror...news-17736.htmlHowever, the Sony a58 you mentioned earlier in your first post; that is a bit unique. Unique as in, it has the body of a DSLR but inside, it has the mechanical or electronics of a mirrorless camera hence it was called DSLT.
Right before I stumbled upon the advert for the used DSLR, I was aiming for the mirrorless Sony a6000 too. In the end I chose DSLR because
1) price - I saved up a few quids
2) lens - The DSLR I bought comes with 18-105 as standard, I can zoom further and I will be sticking to this lens for quite sometime before I decide to upgrade. Meanwhile, the a6000 comes with 16-50 and I could foresee that this lens will not be sufficient for me.
3) overall owning cost - mirrorless systems has a bit more pricier equipments compared to DSLR systems. So, the cheapskate within me chosen the DSLR, considering the fact that I'm going to stick with my choice for a very long time.
4) photography subject - most of my shots involves panning, rolling and tracking shots. So, I need the camera to have 'a little bit of weight' to minimize handshake. I blame the fappy hands.

wow thanks bro~ do give myself more knowledge on this thing .....
but the dealer gave me a price which is so tempting nikon d7000+ 18-105 with 2050 ....
just that what i worry is i dont know what to check for the camera when buying the 2nd hand stuff ....