Hello Ely, welcome to the forum :)
1. The main difference initially started out politically in regards to who should be the next ruler of the Islamic empire.Over time the two groups diverged more and as shia beliefs also started to change and become different then that of Sunni Islam. This can be a lengthy topic to discuss. Here is a short chart showing th difference between there two:
2. The primary goal is to get to paradise. This life is seen as temporary and a test for all with you getting the final grade of pass or fail on Judgement day and then going to where you will end up for eternity.
3. This goal is by following Islam and it's pillars. Which includes doing your obligatory duties, such as 5 daily prayers and voluntary duties such as charity. Allah commands us in the Quran to 'enjoin good and forbid evil', so as civic citizens of this planet we try to emulate the life of the Prophet Muhammad :saws1: as an example to follow.
4. Mosques usually have a carpeted prayer hall for one to sit and read the Quran, listen to sermons and lectures and to stand up and pray in. Normally the female have their own separate prayer area, usually on the second floor over looking the bottom prayer hall. Mosques these are more than just a prayer hall, the whole building consists of an office for administration, restrooms with ablution area, a community multiple purpose hall and maybe an islamic school too if the community is large enough and has the resources. You can find lot of pictures online of inside of a mosque. Here's a few:
5. The mosque is a house of worship and is regarded as the house of God. So one feels happy and excited while also calm and humbled at the same time.
6. The mosques are usually decorated with calligraphy. Depending on the location (east vs west) and resources, some mosques can be very fancy looking while others can be low key blending in with other buildings type. It depends on the community as well, if it's a Muslim majority community or Muslim friendly community then they can be more islamic in design but with current islamophobia trend in the west, usually making the mosques more average and blended in type is the norm. Here are some examples:
7. Mosques are known by their minarets. That is where the caller of prayer used to go to make the call for prayer so it can be heard far and wide. In Muslim countries, they have speakers up there now. In the west, they are shown as a symbol of the building being a mosque. There are some who don't have it and totally blend in so as to not attract attention but that also has the negative effect of no one being able to tell if it's a mosque or just some building, making new comers to the city or travelers who need to prayer to miss out on knowing there is a mosque there.
I hope that helps. If you have more questions, please do ask.