All three are used as a way bring vegetation to the vertical plane. A trellis is a freestanding structure designed to provide a framework for your vines to grow and can be used in conjunction with your pergola structure. Lattice gets mounted to your pergola and can also be used to support the growth of vines, but you will also see it used to create privacy or shade.
Arbors are typically freestanding and usually found in gardens or parks. They are more used as a graphical element to the landscape whereas a pergola is used to define an outdoor living space or leisure area. Pergolas are larger structures and usually customized to fit a persons landscape requirements.
Gazebos are usually freestanding and roofed, but open on all sides. They are often ornamental in nature and provide protection from the elements. They typically have a raised deck to keep you dry from mud during the rain and you'll have plenty of shade. Some gazebos are large enough to accommodate dinner parties, bands, and other outdoor functions.
Patio covers or carports have a solid roof, whereas Pergolas are an overhead frame of open rafters. A patio cover can have a variety of roofing finishes and it is often made to match the existing roofing of the house to better indicate an extension of your living space. A patio cover will provide the ultimate protection from overhead elements. They are best suited for furniture, lighting, fans, shade, tv's, and anything you need maximum protection for in an outdoor environment.
As a large pergola is designed to define an outdoor living space that allows maximum viewing of surrounding elements, a small pergola can be used to define smaller elements around the house or structure. A small pergola can provide shade and definition to your sitting area or walkways. You can also build a small pergola over your front door, garage door, or anywhere that receives too much sunlight. This will help protect the area from sun damage.
A basic or common pergola will consist of posts, beams, lattice and hardware. It can be connected to the house or freestanding. Depending on the situation you may need concrete footers. A typical size pergola will be 10ft long x 10ft wide x 8ft high with a lattice overtop to provide extra shade. It can be made with common wood or pressure treated, but a better solution would be Redwood. Redwood is less susceptible to termites and will require less maintenance which will add years to your pergola.
Since some of the first pergolas were stone structures, using stone columns to support your wood roof canopy can remind us of those early days. Mixing materials of stone and wood can do wonders for your aesthetic and work great in a renaissance or tuscan style environment.
Depending on the design of your outdoor space you may want to paint or stain your pergola. Painting the pergola will require less maintenance and also add some years to the wood by better protecting it from the elements. When it comes to painting, your color options are limitless. This can be a great way to match existing colors or provide a modern design while hiding imperfections in common wood. If you decide to stain the wood, there are still many options in color variance. The main difference is that with stain, the wood grains will be more visible. There are stains that are so dark (ebony) that it almost looks like paint but you will see the wood grain more prominently than if it was paint. A more transparent stain will show off the natural grain of the wood. This is for people who enjoy the natural look of wood.
Redwood and cedar are both more resistant to termites than common wood. Redwood, hence the name, will have a more reddish tone with some noticeable yellowish color variance throughout the grain. Redwood provides a “softer” look, while cedar is a harder wood and typically contains more knots in the grain. Redwood can even be purchased with no knots at all. Cedar will have a more yellowish tint than redwood and there will be less color variance amongst the grain.
Another option to create your pergola is to go with a vinyl or recycled plastic wood alternative. It can almost double your material cost, but if you want to reduce your maintenance maximally, this is a good choice for you. A pergola constructed of this material will be immune to decay and will not need painting. It's a good alternative for places that receive maximum foot traffic.