So which one is better Halides or a T5 3ft? or is there any difference? I'm new to the marine hobby so am just finding out before I make a decision on which one to get it/they will be for a 5ft 580ltr tank thanks.

Very dependant on what you want to keep, or are likely to want to keep in the future.

Most of us have started on one type of lighting (you can switch lighting for a number of things ), and upgraded later as we change our livestock.

Well I want to end up keeping soft corals and fish as well as hard coral so I thought I'd do it once and get all the proper stuff now on yeah the T5 has 4 tubes.

Some people have kept SPS (hard) corals with T5s, quite successfully, but IMO Metal halides are the best option for the long term.

Put up 2 Luminarcs & save swapping lights later

Put up 2 Luminarcs & save swapping lights later

What do those look like and how much do they cost?

have PM'd you

Put up 2 Luminarcs & save swapping lights later

im saying this from experience - if you're seriously going sps later, save yourself money get halides with decent reflectors now! most sps need hard core light and if you want colour, decent lighting will help considerably. other option is combo of halide + t5, seems to work well.

you could just get t5s now, then use them later when you upgrade to MH.

It all depend what you are going to keep. Generally 150/250w halides are more than enough. Most european hobbyist are starting to use only t5s as you can keep all corals under this light.

T5s gives a more even lighting vs metal halide which is bright under the halide however light drops quite a lot once you move away from the centre.

only thing i dont like about t5s is that you dont get glitter lines in the water.

It can come down to moneys as good looking lights cost money.