Talking is the first step in getting to know someone. It's the stage where you ask questions about each other's hobbies, interests, and backgrounds. Appointments are when you've had a few dates but nothing is official yet. Being in a relationship is a more serious commitment and can mean different things to different people.
In the conversation stage, it's unlikely that you'll meet each other's parents or family members. It's easy to assume that talking and going out with someone is based on whether they are physically involved or not, such as kissing or holding hands. This is the time when people can get to know each other without making any commitments or doing the work needed for dating. When two people are dating, they usually go out on dates and spend time together.
According to a Google study of over 300 young adults aged 18-24, more than 20% said that texting could count as a date. They may choose to be sexually exclusive but still date other people, be sexually open but only date each other, or enter into an exclusive relationship where both physical and emotional aspects are reserved for each other. This is how you know that you have gone beyond talking and have entered the dating stage. If someone you've been talking to does something special for you, it's a sign that things could be progressing to the dating stage.
One downside of the conversation stage is that it can be easy to get stuck without ever progressing to real dates.