Understand GitLab CI/CD better

Question

Did I understand this correctly, that stages will run in parallel if they have the same name?

stages:
  - build

rust-latest:
  stage: build
  image: rust:latest
  script:
    - apt-get update && apt-get -y install libgccjit-6-dev
    - cargo build --verbose
    - cargo test --verbose -- --nocapture

rust-nightly:
  stage: build
  image: rustlang/rust:nightly
  script:
    - apt-get update && apt-get -y install libgccjit-6-dev
    - cargo build --verbose
    - cargo test --verbose
  allow_failure: true

And that the stages should be the same if they are independent? Will this make deployments quicker compared to:

stages:
  - build
  - build2

rust-latest:
  stage: build
  image: rust:latest
  script:
    - apt-get update && apt-get -y install libgccjit-6-dev
    - cargo build --verbose
    - cargo test --verbose -- --nocapture

rust-nightly:
  stage: build2
  image: rustlang/rust:nightly
  script:
    - apt-get update && apt-get -y install libgccjit-6-dev
    - cargo build --verbose
    - cargo test --verbose
  allow_failure: true

Answer 1

No, jobs (which rust-latest and rust-nightly are examples of) will run in parallel if they are in the same stage (of which you only have one, build).