The Connector and Line Tools work identically to each other.
The Connector Tool lets you draw a line forced to turn at right angles where necessary and the Line Tool draws a straight line between whichever endpoints you select, with no turns. To draw either a connector or a line, select the appropriate tool from the Toolbar, place your cursor where you want your connector or line to start and click and drag to your desired endpoint.
Once you’ve drawn a line or connector you’ll notice a characteristic about each endpoint: if it’s a connector with more than two segments, each middle segment has a little circle. These circles work like the squares around the boundary boxes of shapes. If you click and drag on one of the circles, you’ll only adjust that segment of the line/connector. If you click anywhere else, you’ll move the whole line.
Frequently, you’ll want to connect the end of a line to a shape so that if the shape moves, the line will stick to the shape. When you select a line, you’ll see that all the shapes in your diagram become flanked with little ‘ + ‘ symbols. There should be one in the middle of each shape as well. These ‘ + ‘ symbols are standard connection points. If you drag the endpoint of a line or connector to one, you’ll see the little circle turn red. That indicates the line is locked to the connection point. From then on, if you move the shape, the line will remain connected.