# Question about two variables?
**URL:** https://discourse.julialang.org/t/question-about-two-variables/82094
**Category:** General Usage
**Created:** [June 1, 2022, 11:24pm UTC](https://discourse.julialang.org/t/question-about-two-variables/82094 "2022-06-01T23:24:12Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@Raymond](https://discourse.julialang.org/u/Raymond)
#### Post date: [June 1, 2022, 11:24pm UTC](https://discourse.julialang.org/t/question-about-two-variables/82094/1 "2022-06-01T23:24:12Z")
Dear all,
What is the difference between `foo` and `bar` below?
```julia
julia> foo = [1, 2, 3]
3-element Vector{Int64}:
1
2
3
julia> bar = [1; 2; 3]
3-element Vector{Int64}:
1
2
3
julia> foo === bar
false
julia> varinfo()
name size summary
–––––––––––––––– ––––––––––– –––––––––––––––––––––––
Base Module
Core Module
InteractiveUtils 252.883 KiB Module
Main Module
ans 1 byte Bool
bar 64 bytes 3-element Vector{Int64}
foo 64 bytes 3-element Vector{Int64}
```
---
### Author:  [@Oscar\_Smith](https://discourse.julialang.org/u/Oscar_Smith)
#### Post date: [June 1, 2022, 11:25pm UTC](https://discourse.julialang.org/t/question-about-two-variables/82094/2 "2022-06-01T23:25:26Z")
`===` returns whether two objects are indistinguishable from each other. For mutable structs, this means they need to be the same object.
If you write `foo[1] = 3`, `bar[1]` will still be `1` so they are not the same object.
---
### Author:  [@Raymond](https://discourse.julialang.org/u/Raymond)
#### Post date: [June 1, 2022, 11:31pm UTC](https://discourse.julialang.org/t/question-about-two-variables/82094/3 "2022-06-01T23:31:52Z")
I see. Thanks.
But I want to know what’s the difference between `[1, 2, 3]` and `[1; 2; 3]`?
In Julia, they are both `3-element Vector{Int64}`.
---
### Author:  [@Raymond](https://discourse.julialang.org/u/Raymond)
#### Post date: [June 1, 2022, 11:34pm UTC](https://discourse.julialang.org/t/question-about-two-variables/82094/4 "2022-06-01T23:34:25Z")
```julia
julia> foo = [1, 2, 3]
3-element Vector{Int64}:
1
2
3
julia> bar = [1; 2; 3]
3-element Vector{Int64}:
1
2
3
julia> foo == bar
true
julia> typeof(foo)
Vector{Int64} (alias for Array{Int64, 1})
julia> typeof(bar)
Vector{Int64} (alias for Array{Int64, 1})
```
---
### Author:  [@Oscar\_Smith](https://discourse.julialang.org/u/Oscar_Smith)
#### Post date: [June 1, 2022, 11:34pm UTC](https://discourse.julialang.org/t/question-about-two-variables/82094/5 "2022-06-01T23:34:26Z")
There isn’t a difference here. The difference between the two syntaxes is that `;` concatenates. So
```julia
julia> [[1,2], [3,4]]
2-element Vector{Vector{Int64}}:
[1, 2]
[3, 4]
julia> [[1,2]; [3,4]]
4-element Vector{Int64}:
1
2
3
4
```
---
### Author:  [@Raymond](https://discourse.julialang.org/u/Raymond)
#### Post date: [June 1, 2022, 11:35pm UTC](https://discourse.julialang.org/t/question-about-two-variables/82094/6 "2022-06-01T23:35:56Z")
Oh, get it. Thanks so much.
---
### Author:  [@jling](https://discourse.julialang.org/u/jling)
#### Post date: [June 1, 2022, 11:45pm UTC](https://discourse.julialang.org/t/question-about-two-variables/82094/7 "2022-06-01T23:45:15Z")
FYI
[https://docs.julialang.org/en/v1/manual/arrays/#man-array-concatenation](https://docs.julialang.org/en/v1/manual/arrays/#man-array-concatenation)