Aru baito (アルバイト), or baito for short is the term used to describe someone who isn't fully committed to work for a company for a long period of time. An employee would consider their job not a career, not their long term goal.
Joukin (常勤) is the opposite of baito. Workers who are joukin are fully committed to the company they are working for. Employees are expected to work hard and devote their time and energy to their job.
The reason these two words aren't well translated into part time and full time jobs is because the amount of hours one works is most often the same. Sometimes the pay is the same as well, depending on the company.
Hataraku (働く) is a verb that means to work.
Father is working with son = otousan wa musuko to hataraite iru
Doctor works at hospital = isha wa byouin de hataraku
Where do you work = doko de hatarakimasu ka (どこで働きますか)
At any time of day, especially in downtown areas you will see salaryman (sarariiman サラリーマン). This word refers to those who are working for corporations on a salary based income. But most often used to point out men who are wearing suits, as they either do or appear as if they work for a cooperation.
It's not uncommon to see a salary man sleeping on the train or even the ground in Japan. Due to the hard working environment, workers are very tired.