A US permanent resident card is different from citizenship and as a PR, you have to chances to do certain things, like stay in the US indefinitely, but you also have a number of restrictions as well.
A US permanent resident staying lawfully is a person granted the right and ability to stay in the United States forever. A person with a permanent resident is given a green card. This is basically a photo identification card, stating he is a permanent resident.
A permanent resident has a right to work in the US. They can also petition for a family member to gain permanent residence too. This has its loopholes and they can take a long time on the waiting list.
Permanent residents will still to be the citizen of his main country. Because of this, when traveling, you must possess the passport of your initial country plus your green card. Your green card would be used when you want to reenter the US.
As a US permanent resident, you do not require a work permit to get a job. Most state jobs are open to you and do not require your citizenship.
Limitation of a US permanent resident to a citizen.
Most people tend to live a lot of their lives as a US permanent resident without seeking citizenship. But there are certain limitations to just being a PR and you might want to consider applying for citizenship.
A major disadvantage is when you leave the Country and stay out of it for 6 months and above, reentry would be quite a problem. It would be assumed you want to give up your PR status and reentry could be a challenge. Another disadvantage being you can be denied access you enter back into the country but they can not deny a citizen.
You also do not have the right to vote and you would be taxed differently from citizens.
Your PR status can be revoked, unlike your citizenship. It can be revoked if you commit a serious crime plus you must be on your best behaviors at all times. Staying away from protests, riots, etc.
You also cannot apply for permanent federal Jobs which would require your status as a citizen. As a PR, you cannot sponsor your parents for a green card as this is an immigration benefit that favors citizens.
Being a US resident can be cool but due to these limitations and a few more, applying for citizenship would be a good alternative.