Specifically, dating is about getting to know someone romantically, whereas being in a relationship means that dating couples have already committed to each other and intend to (hopefully) cultivate their connection at least for the time being. Here are some very salient differences between being in a relationship and dating someone, just in case you're confused. The main difference between dating and being in a relationship is a level of commitment, and generally, an honest and open chat with your partner. They can see each other on regular date nights, but ultimately, they spend more time cultivating their lives outside of each other.
In the first, both of you have decided not to date anyone other than each other, whereas, in the latter, you have decided to take things seriously and move forward to staying together or being alone together. Exclusively going on dates means that you and your partner have talked about your future and have agreed to go out just for the time being. Some people like to date each other exclusively, while others like to date other people and don't want to commit to just one person. Going on dates exclusively means that the two of you have decided to take your relationship one step further and agree to only date each other for a while.
You may not know the person well enough after a month and a date or two, or you may feel like you know the person well very quickly. As mentioned above, you don't have any responsibility, so you're also free to date other people. Previously in your stage of dating, there are no conversations about “us because you don't plan to build a future together with the person you date. The difference here is that you choose to date someone exclusively by investing more energy and time with them.
Maybe you schedule an appointment right after a visit to the gym and have no intention of showering first. They go out to find out if there is a possibility for them to enter into a serious and committed long-term relationship with each other. It starts with the online texting stage, the first date and then deciding if one wants to continue with this or not.