HI....I entered the marine scene after about six months FW experience and outside of a few basic skills, they are two very different systems. The really big issue for you here is mini-reef vs nano-reef, again in some ways very similar and in others drastically different.
A nano-reef is not going to let you keep many of the things you mentioned, including anemones and sea stars. Those animals require large tanks which have matured. The anemone in particular requires high lighting and expert care. Nano reefs are small tanks and don't leave a lot of room for error. While a mini-reef may reach a 'cruising speed', a nano usually requires 5-10 minutes of some kind of work every day.
Although the apparent initial outlay of money for a nano tank looks very affordable, the upgrades necessary for 'self contained' systems can far exceed the initial cost. Also, the cost in losses of livestock in a nano tank can really pad the bill. The initial costs of setting up a 55 may be more but a nano can catch up very quickly.
Filtration on both tanks is basically your live rock, live sand and powerheads for circulation. Canister filters are generally not well liked as the amount of detritus they collect can cause nutrient/nitrate problems.
Overall, whether you choose a nano reef or mini-reef, the key to success is to spend a period of time doing reading and research. Decide on a system and, perhaps, run your initial setup plans by some people here for advice and guidance. Both systems will have their difficult moments. A nano reef will place stocking restrictions on you and will require you to develop superb water husbandry techniques. A larger system will start out with more plumbing, equipment and initial live rock investment. Good luck and let us know what you decide. SH
