1. Syntax: One of the main differences between C++ and Smalltalk is their syntax. C++ is a statically typed language with C-like syntax, which means that variables must be declared with their types and follow a specific syntax. On the other hand, Smalltalk is a dynamically typed language with more flexible syntax, where variables do not need to be declared with their types and the syntax is more natural language-like.

2. Object-Oriented Paradigm: While both C++ and Smalltalk support object-oriented programming, the way they handle objects is different. In C++, objects are created by defining a class and then instantiating it with the "new" keyword, whereas in Smalltalk, objects are created by sending messages to classes using class methods. This difference in object creation and behavior affects the overall programming style and approach in each language.

3. Memory Management: Another notable difference between C++ and Smalltalk is their memory management. C++ uses manual memory management, meaning that the programmer needs to explicitly allocate and deallocate memory for objects using new and delete keywords. On the other hand, Smalltalk uses automatic memory management through a process called garbage collection, where objects that are no longer needed are automatically reclaimed by the system. This difference in memory management can have implications on the complexity and bug-proneness of code in each language.

4. Compilation vs Interpretation: C++ is a compiled language, which means that the source code is compiled into machine code before it can be executed. Smalltalk, in contrast, is an interpreted language, where the source code is executed directly by an interpreter without prior compilation. This difference in execution method has implications on the performance and deployment of code in each language, with compiled code generally being faster but requiring separate builds for different platforms.

5. Language Features: C++ and Smalltalk also differ in terms of the features they provide. C++ is a low-level language that offers features such as pointers, direct memory manipulation, and bitwise operations, which allow fine-grained control over the hardware. Smalltalk, on the other hand, is a high-level language that focuses on simplicity and abstraction, providing features like reflection, dynamic typing, and a powerful messaging system that allows objects to communicate with each other.

6. Community and Ecosystem: Finally, C++ and Smalltalk have distinct communities and ecosystems surrounding them. C++ has a large and active community with extensive libraries, frameworks, and tools available for various domains and platforms. Smalltalk, although smaller in comparison, also has a dedicated community with a focus on Smalltalk's unique strengths and ideals, such as the Smalltalk-80 standard and the Squeak/Pharo dialects.

In Summary, C++ and Smalltalk differ in their syntax, object-oriented paradigm, memory management, execution method, language features, and community ecosystem, making them distinct programming languages with different strengths and use cases.