总结版
- 根据内外科分physician / internist和surgeon。
- 根据学医阶段，分为resident和attending。
- 按学科范围划分的话，就有了specialist，与之相对的就是general practitioner / primary care physician。
- 所有的医生统称为doctor。
详解版
Physician / Internist / Surgeon
Collins Dictionary关于Physician的解释：
“A person legally qualified to practise medicine, esp one specializing in areas of treatment other than surgery; doctor of medicine.”
Wikipedia关于Physician的定义：
“A physician, medical practitioner, medical doctor, or simply doctor, is a professional who practises medicine, which is concerned with promoting, maintaining, or restoring health through the study, diagnosis, prognosis and treatment of disease, injury, and other physical and mental impairments.”
根据英语释义，Physician可以指医生，也可以指内科医生，具体含义要根据实际情景而定。比如，医患关系可译为physician-patient relationship。
而internist则专指内科医生。Collins Dictionary的相关定义：
“An internist is a doctor who specializes in the nonsurgical treatment of disorders occurring inside people’s bodies.”
内科医生负责研究、诊断内科疾病，为患者提供非手术治疗。治疗方法主要为药物治疗。举个例子，感冒去医院可以挂内科，内科医生根据病人的症状开出处方，而不需要手术。
Surgeon在Collins Dictionary的相关定义：
“A surgeon is a doctor who is specially trained to perform surgery.”
Surgeon指外科医生，指专修外科或专修人体某个部分的外科专科医生，这类医生一般需对患者进行手术治疗。例如，阑尾炎发作需要进行切除手术，这时候就需要外科医生。
Attending / Resident
Attending (physician or doctor)
Merriam Webster Dictionary的定义：
“Attending serves as a physician or surgeon on the staff of a hospital or similar health-care facility and having primary responsibility over the treatment of a patient and often supervising treatment given by interns, residents, and fellows.”
Attending指主治医生。在美国，当你完成了住院医生培训和其他专业培训，就成为了一名主治医生，可以独立行医。可以是外科主治医生，也可以是内科主治医生。在医院工作时，主治医生需要指导、监督实习医生、住院医生的诊疗。
Resident (physician)
Cambridge Dictionary的定义：
“Resident refers to a doctor who is still training, and who works in a hospital.”
Wikipedia上的解释：
“Resident refers to a qualified physician who holds the degree of MD, DPM, etc., and practices medicine, usually in a hospital or clinic, under the direct or indirect supervision of a senior clinician registered in that specialty such as an attending physician or consultant.”
根据以上英文释义，Resident指住院医生，已完成医学院学习，正在医院接受医学培训，不能独立行医，诊治时需要接受上级医生（主治医生及以上）的指导与监督。主要负责基本医疗工作，包括收治病人、记录病程、在上级医师指导下开医嘱、进行某些临床操作等。
Wikipedia还提到：
“An individual engaged in residency may be referred to as a resident, house officer (staff), registrar or trainee depending on the jurisdiction.”地区不同，住院医生的称呼不同，主要有resident、house officer (staff)、registrar或trainee。
Specialist / General Practitioner / Primary Care Physician
Specialist
Collins Dictionary的相关定义：
“A specialist is a person who has a particular skill or knows a lot about a particular subject.”Specialist指专科医生，是专攻某一医学领域的医生，为病人提供系统、针对性的医疗服务，是医疗服务的研究者、专家。
General Practitioner
Wikipedia的相关定义：
“A general practitioner (GP) is a medical doctor who treats acute and chronic illnesses and provides preventive care and health education to patients. Their duties are not confined to specific organs of the body.”
General Practitioner指全科医生，具备综合性的医疗知识，并不限于某一领域。一般以门诊形式处理急症或慢性病，在没有疾病时负责按不同年龄需要进行预防教育和健康普查等工作。症状轻微、易于治疗的患者可由全科医生进行初步诊断诊断和治疗。若需到专科就诊，一般需由全科医生推荐至专科医生，可以得到专业而又针对性的诊治。
General Practitioner目前在英国较为常见，美国过去也有出现，但目前在美国医疗体系中更多使用Primary care physician。
Primary Care Physician (provider)
Wikipedia的相关释义：
“To become primary care physicians, medical school graduates then undertake postgraduate training in primary care programs, such as family medicine (also called family practice or general practice in some countries), pediatrics or internal medicine.”
Primary care physician，初级保健医生。有些医学生毕业后继续参加初级保健项目的培训，主要方向有家庭医学科（有些国家称为家庭保健或全科医疗）、儿科或内科。因此，初级保健医生主要分为家庭医生、全科医生、老年病医生和普通儿科医生，以及负责新病诊断、慢性病管理、提供预防保健护理和健康保护的医生。
Doctor
Collins Dictionary：“A doctor is someone who is qualified in medicine and treats people who are ill. A dentist or veterinarian can also be called doctor.”Doctor是普通用词，泛指各科医生，即一切有行医资格的人。
