# Direct substitution vs "subs" method

Suppose I define

```
var('a b c')
formula = a^2 + 5*b + c
```

Then I would like to substitute some values, like a=2, b=2 and c=4. As far as I'm aware, there are two options to do this:

```
formula(a=2, b=2, c=4)
```

and

```
formula.subs(a=2, b=2, c=4)
```

In this particular case, is there any difference between this two options? Is there any difference in some other case(s)?

Thanks in advance for you answers!