I intend to take the train from Nice to Avignon in December. Is it better to book the train tickets in advance or it is ok to buy the tickets on the day of travel? Will the price difference be great?
You can look up the price for that date at
That route is served by both TGV and TER trains
It will take two trains to get there meaning you will have to transfer to another train
Any train listed in the results that is TGV or high speed rail the price is going to go up if you do not book in advance.
Any train combination listed as TER the price will stay the same or lower.
If you give the specific date and time that you want to leave Nice to Avignon you can get more definite answer here.
There are direct trains from Nice to Avignon TGV: they are by far the better trains to take, and should be booked in advance.
Once in Avignon TGV, you either take a short train ride to Avignon Centre (you can book this with your TGV ticket if you book from Nice to Avignon Centre) or taxi/uber for a few miles (cost unknown to me, but can't be more than 25-30 euros).
Once past Marseille, the high-speed trains will not live up to their name as the rail beds do not permit such speeding. The TGV's probably make fewer stops and certainly are comfortable at any speed.
Find a direct train that fits your schedule and buy in advance if possible, it will be cheaper and you won't risk a full train if it's high season.
Thank you for the suggestions. After researching, I have two options
1) Take a direct evening train to Avignon for around 63 euro
2) Take a morning train to Marseilles, tour Marseilles, then take an evening train to Avignon. Total around 50 euro.
Which is a better choice? For choice 2, I'll be able to tour Marseilles and pay a cheaper price. However, I'm not sure if it is worth the hassle.
Marseille is nice, so visit it if you can. You can buy the 24 hour transit pass for 5.20 euros and see the sights.
There should be a number of train journeys, though, that are tgv from avignon, small connection, then ter to nice ville that will save you money and doesn't require you to stay in marseille for the day. Are you looking at tickets on en.oui.sncf ? There's no real point to taking the direct tgv from Avignon since it costs more and has fewer departure options but takes the same amount of travel time.