Context will tell you everything.
If someone is standing in front of you carrying a steaming teapot and an empty cup and says "Would you like tea?" then they are offering it to you right now.
If someone says at 2pm "Would you like tea at 4pm?" then they are asking you to make a decision now about something you can have two hours later. Of course, it's possible that by 4pm, you won't want tea any more but you're being asked to decide now.
If someone says "Would you like tea if it were delivered by Brad Pitt naked?" then the suggestion would be that normally you don't like tea but the person thinks you might change your mind in different circumstances. Here, it's a hypothetical.
With the question "Would you like tea?" referring to right now, it means "Do you want tea?" I think you probably know exactly what tense that question is, don't you?