The main differences are as follows:
1) The train route is, in my opinion, more photogenic.
There is a great, if brief, crossing of the 25 de Abril Bridge which allows a wonderful view, in the day time down along the Tejo from Lisbon to Cascais.
There is then a lovely run through the Alentejo, which gives one a real taste of rural southern Portugal.
Be aware that you have to change trains at Tunes junction to a local rattler that wanders its way through the Western Algarve to Lagos. Again you get to see more than you would in the bus.
2) The trains from Lisbon to Tunes and onward to Faro have buffet cars onboard so that you can get up, wander around, have a coffee or a glass of wine, and thus is less restricting than a bus.
3) The two main bus routes follow the A2 tool main motorway from Lisbon the Algarve and then the A22 Via de Infante Algarve Arterial Motorway to Lagos.
4) The EVA buses from Lisbon Sete Rios only take 3hrs45 mins but are non-stop to Lagoa and then stop only in Portimão, Praia da Rocha, and then Lagos. They have pokey onboard toilets.
5) Renex buses from Lisbon Gare Oriente follow the same route to then end of the A2 motorway but then have more stops along the Western Algarve. They do stop for 15 minutes en route for Coffee etc. They can take up to +4 hours.
6) There are also a couple of daily Rede Expressos buses from Lisbon Sete Rios that follow rural routes through via Messines or via Odemira and Aljezur to Lagos. Again these take +4 hours.
For trains, you can by tickets/make reservations at most self-respecting CP(Portuguese Railways) stations in Lisbon. I would recommend Entrecampos,Gare Oriente,Stª.Apolonia, and I think from memory, Restauradores Station (Sintra Line).
For the buses:
1) EVA/Rede Expressos - Lisbon Sete Rios Bus Station Ticket Office (Metro/CP Station Sete Rios)
2) RENEX - Lisbon Gare Oriente Bus Station Ticket Office (Metro/CP Station Sete Rios)
As regards purchasing tickets at the tourist office at Lisbon Airport or Restauradores/Liberdade not sure, Maybe someone can advise?
Sorry there's too much information. It's the first time we've had that complaint as far as I know.
