"Be friendly with sb" 和 "be friendly to sb" 都表示友好相处，但前者侧重于建立并维持双方之间的友好关系，通常用于较为亲近的人际关系；而后者则更强调一方对待他人的友善姿态和行为，并适用于广泛的环境和关系。它们在释义、用法、使用环境、影响范围和形象上存在一些区别，具体内容如下所示。
1. 释义区别：
"be friendly with sb"：表示与某人保持友好关系，彼此之间有互动和交往。
"be friendly to sb"：表示对某人友善和热情，表现出善意和友好态度。
例句：
He is friendly with his neighbors and often goes out with them.（他与邻居们保持着友好关系，并经常一起外出。）
The shopkeeper is always friendly to her customers.（店主对顾客总是友善的。）
2. 用法区别：
"be friendly with sb"通常强调双方之间互相建立了友好的关系。
"be friendly to sb"则侧重于单方面表达友好和善意。
例句：
Lisa is friendly with her colleagues at work.（丽莎与她的同事们关系友好。）
The hotel staff are always friendly to the guests.（酒店员工总是对客人友好的。）
3. 使用环境区别：
"be friendly with sb"更常用于描述具体的人际关系和社交圈内的友好互动。
"be friendly to sb"通常用于形容对待他人时所展现的友善态度。
例句：
Mark is friendly with his classmates and often helps them with their studies.（马克与他的同学们关系友好，经常帮助他们学习。）
The teacher is always friendly to her students and encourages them to ask questions.（老师对学生总是友善，并鼓励他们提问。）
4. 影响范围区别：
"be friendly with sb"强调双方之间建立了较为密切的友好关系。
"be friendly to sb"则更侧重于对各种人群展现友善态度。
例句：
Tom is friendly with his best friend; they share everything with each other.（汤姆与他最好的朋友关系密切，彼此分享一切。）
She is always friendly to everyone she meets, regardless of their background.（她对遇到的每个人都友好，不论他们的背景如何。）
5. 形象区别：
"be friendly with sb"可认为双方具有更深入的交情，形成了比较亲密的关系。
"be friendly to sb"则可能给人留下一种单方面友善和善意的印象。
例句：
Jane is friendly with her colleagues, they often have lunch together and share their personal stories.（简与她的同事们关系亲近，他们经常一起吃午饭并分享个人故事。）
The salesperson is friendly to customers, always greeting them warmly and offering assistance.（销售人员对客户友好，总是热情地问候并提供帮助。）